diff --git a/vpi/sys_clog2.c b/vpi/sys_clog2.c
index bd6517837..31cfcf51b 100644
--- a/vpi/sys_clog2.c
+++ b/vpi/sys_clog2.c
@@ -58,7 +58,7 @@ static unsigned is_numeric_obj(vpiHandle obj)
 /*
  * Check that the function is called with the correct argument.
  */
-static PLI_INT32 sys_clog2_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_clog2_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv, arg;
@@ -106,7 +106,7 @@ static PLI_INT32 sys_clog2_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_clog2_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_clog2_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_convert.c b/vpi/sys_convert.c
index 4b296ff61..88cf7292c 100644
--- a/vpi/sys_convert.c
+++ b/vpi/sys_convert.c
@@ -93,7 +93,7 @@ static void error_message(vpiHandle callh, const char* msg)
 static PLI_INT32 sizetf_32 (PLI_BYTE8*x) { return 32; }
 static PLI_INT32 sizetf_64 (PLI_BYTE8*x) { return 64; }
 
-static PLI_INT32 sys_convert_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_convert_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -123,7 +123,7 @@ static PLI_INT32 sys_convert_compiletf(PLI_BYTE8*name)
     return 0;
 }
 
-static PLI_INT32 sys_bitstoreal_calltf(PLI_BYTE8*user)
+static PLI_INT32 sys_bitstoreal_calltf(ICARUS_VPI_CONST PLI_BYTE8*user)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     vpiHandle arg  = (vpiHandle) vpi_get_userdata(callh);
@@ -147,7 +147,7 @@ static PLI_INT32 sys_bitstoreal_calltf(PLI_BYTE8*user)
     return 0;
 }
 
-static PLI_INT32 sys_itor_calltf(PLI_BYTE8*user)
+static PLI_INT32 sys_itor_calltf(ICARUS_VPI_CONST PLI_BYTE8*user)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     vpiHandle arg  = (vpiHandle) vpi_get_userdata(callh);
@@ -167,7 +167,7 @@ static PLI_INT32 sys_itor_calltf(PLI_BYTE8*user)
     return 0;
 }
 
-static PLI_INT32 sys_realtobits_calltf(PLI_BYTE8*user)
+static PLI_INT32 sys_realtobits_calltf(ICARUS_VPI_CONST PLI_BYTE8*user)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     vpiHandle arg  = (vpiHandle) vpi_get_userdata(callh);
@@ -197,7 +197,7 @@ static PLI_INT32 sys_realtobits_calltf(PLI_BYTE8*user)
     return 0;
 }
 
-static PLI_INT32 sys_rtoi_calltf(PLI_BYTE8*user)
+static PLI_INT32 sys_rtoi_calltf(ICARUS_VPI_CONST PLI_BYTE8*user)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     vpiHandle arg  = (vpiHandle) vpi_get_userdata(callh);
diff --git a/vpi/sys_deposit.c b/vpi/sys_deposit.c
index b78acb624..74eae09d2 100644
--- a/vpi/sys_deposit.c
+++ b/vpi/sys_deposit.c
@@ -22,7 +22,7 @@
 # include  <assert.h>
 # include  <string.h>
 
-static PLI_INT32 sys_deposit_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_deposit_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -69,7 +69,7 @@ static PLI_INT32 sys_deposit_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_deposit_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_deposit_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, target, value;
       s_vpi_value val;
diff --git a/vpi/sys_display.c b/vpi/sys_display.c
index b8b4a317b..fd0cc1b4b 100644
--- a/vpi/sys_display.c
+++ b/vpi/sys_display.c
@@ -1066,7 +1066,7 @@ static int sys_check_args(vpiHandle callh, vpiHandle argv, PLI_BYTE8*name,
 }
 
 /* Common compiletf routine. */
-static PLI_INT32 sys_common_compiletf(PLI_BYTE8*name, int no_auto,
+static PLI_INT32 sys_common_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name, int no_auto,
                                       int is_monitor)
 {
       vpiHandle callh, argv;
@@ -1101,14 +1101,14 @@ static PLI_INT32 sys_common_compiletf(PLI_BYTE8*name, int no_auto,
 }
 
 /* Check the $display, $write, $fdisplay and $fwrite based tasks. */
-static PLI_INT32 sys_display_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_display_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
 	/* These tasks can have automatic variables and are not monitor. */
       return sys_common_compiletf(name, 0, 0);
 }
 
 /* This implements the $display/$fdisplay and the $write/$fwrite based tasks. */
-static PLI_INT32 sys_display_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_display_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, scope;
       struct strobe_cb_info info;
@@ -1221,14 +1221,14 @@ static PLI_INT32 strobe_cb(p_cb_data cb)
 }
 
 /* Check both the $strobe and $fstrobe based tasks. */
-static PLI_INT32 sys_strobe_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_strobe_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
 	/* These tasks can not have automatic variables and are not monitor. */
       return sys_common_compiletf(name, 1, 0);
 }
 
 /* This implements both the $strobe and $fstrobe based tasks. */
-static PLI_INT32 sys_strobe_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_strobe_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh, argv, scope;
       struct t_cb_data cb;
@@ -1364,7 +1364,7 @@ static PLI_INT32 monitor_cb_1(p_cb_data cause)
       return 0;
 }
 
-static PLI_INT32 sys_monitor_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_monitor_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -1373,7 +1373,7 @@ static PLI_INT32 sys_monitor_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_monitor_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_monitor_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh, argv, scope;
       unsigned idx;
@@ -1452,20 +1452,20 @@ static PLI_INT32 sys_monitor_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_monitoron_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_monitoron_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       monitor_enabled = 1;
       monitor_cb_1(0);
       return 0;
 }
 
-static PLI_INT32 sys_monitoroff_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_monitoroff_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       monitor_enabled = 0;
       return 0;
 }
 
-static PLI_INT32 sys_swrite_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_swrite_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
   vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
   vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -1494,7 +1494,7 @@ static PLI_INT32 sys_swrite_compiletf(PLI_BYTE8 *name)
   return 0;
 }
 
-static PLI_INT32 sys_swrite_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_swrite_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
   vpiHandle callh, argv, reg, scope;
   struct strobe_cb_info info;
@@ -1532,7 +1532,7 @@ static PLI_INT32 sys_swrite_calltf(PLI_BYTE8 *name)
   return 0;
 }
 
-static PLI_INT32 sys_sformat_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_sformat_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
   vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
   vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -1581,7 +1581,7 @@ static PLI_INT32 sys_sformat_compiletf(PLI_BYTE8 *name)
   return 0;
 }
 
-static PLI_INT32 sys_sformat_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_sformat_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
   vpiHandle callh, argv, reg, scope;
   struct strobe_cb_info info;
@@ -1642,7 +1642,7 @@ static PLI_INT32 sys_end_of_compile(p_cb_data cb_data)
       return 0;
 }
 
-static PLI_INT32 sys_timeformat_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_timeformat_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh   = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv  = vpi_iterate(vpiArgument, callh);
@@ -1718,7 +1718,7 @@ static PLI_INT32 sys_timeformat_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_timeformat_calltf(PLI_BYTE8*xx)
+static PLI_INT32 sys_timeformat_calltf(ICARUS_VPI_CONST PLI_BYTE8*xx)
 {
       s_vpi_value value;
       vpiHandle sys   = vpi_handle(vpiSysTfCall, 0);
@@ -1781,7 +1781,7 @@ static const char *pts_convert(int value)
       return string;
 }
 
-static PLI_INT32 sys_printtimescale_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_printtimescale_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh   = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv  = vpi_iterate(vpiArgument, callh);
@@ -1824,7 +1824,7 @@ static PLI_INT32 sys_printtimescale_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_printtimescale_calltf(PLI_BYTE8*xx)
+static PLI_INT32 sys_printtimescale_calltf(ICARUS_VPI_CONST PLI_BYTE8*xx)
 {
       vpiHandle callh   = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv  = vpi_iterate(vpiArgument, callh);
@@ -1849,7 +1849,7 @@ static PLI_INT32 sys_printtimescale_calltf(PLI_BYTE8*xx)
       return 0;
 }
 
-static PLI_INT32 sys_fatal_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_fatal_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -1873,7 +1873,7 @@ static PLI_INT32 sys_fatal_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_severity_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_severity_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_fileio.c b/vpi/sys_fileio.c
index 0b13f4bb8..c1063c095 100644
--- a/vpi/sys_fileio.c
+++ b/vpi/sys_fileio.c
@@ -30,7 +30,7 @@
 /*
  * Implement the $fopen system function.
  */
-static PLI_INT32 sys_fopen_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_fopen_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv;
@@ -71,7 +71,7 @@ static PLI_INT32 sys_fopen_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_fopen_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fopen_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -177,7 +177,7 @@ static PLI_INT32 sys_fopen_calltf(PLI_BYTE8*name)
  * from Chris Spear's File I/O for Verilog.
  */
 
-static PLI_INT32 sys_fopenrwa_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fopenrwa_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -205,7 +205,7 @@ static PLI_INT32 sys_fopenrwa_calltf(PLI_BYTE8*name)
 /*
  * Implement $fclose system function
  */
-static PLI_INT32 sys_fclose_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fclose_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -243,7 +243,7 @@ static PLI_INT32 sys_fclose_calltf(PLI_BYTE8*name)
 /*
  * Implement $fflush system function
  */
-static PLI_INT32 sys_fflush_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fflush_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -291,7 +291,7 @@ static PLI_INT32 sys_fflush_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_fputc_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fputc_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -335,7 +335,7 @@ static PLI_INT32 sys_fputc_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_fgets_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_fgets_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -382,7 +382,7 @@ static PLI_INT32 sys_fgets_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_fgets_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fgets_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -446,7 +446,7 @@ static PLI_INT32 sys_fgets_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_fread_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_fread_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -571,7 +571,7 @@ static unsigned fread_word(FILE *fp, vpiHandle word,
       return rtn;
 }
 
-static PLI_INT32 sys_fread_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fread_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -705,7 +705,7 @@ static PLI_INT32 sys_fread_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_ungetc_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_ungetc_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -752,7 +752,7 @@ static PLI_INT32 sys_ungetc_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_fseek_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_fseek_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -815,7 +815,7 @@ static PLI_INT32 sys_fseek_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_fseek_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fseek_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -885,7 +885,7 @@ static PLI_INT32 sys_fseek_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_common_fd_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_common_fd_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -945,7 +945,7 @@ static PLI_INT32 sys_common_fd_calltf(PLI_BYTE8*name)
 /*
  * Implement the $ferror system function.
  */
-static PLI_INT32 sys_ferror_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_ferror_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv;
@@ -1000,7 +1000,7 @@ static PLI_INT32 sys_ferror_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_ferror_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_ferror_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_finish.c b/vpi/sys_finish.c
index 0a555c7e3..077de849e 100644
--- a/vpi/sys_finish.c
+++ b/vpi/sys_finish.c
@@ -20,7 +20,7 @@
 #include "sys_priv.h"
 #include <string.h>
 
-static PLI_INT32 sys_finish_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_finish_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv;
       s_vpi_value val;
diff --git a/vpi/sys_fst.c b/vpi/sys_fst.c
index 782fc9ede..8ca1ee26f 100644
--- a/vpi/sys_fst.c
+++ b/vpi/sys_fst.c
@@ -276,7 +276,7 @@ __inline__ static int install_dumpvars_callback(void)
       return 0;
 }
 
-static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpoff_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -303,7 +303,7 @@ static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpon_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -330,7 +330,7 @@ static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpall_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpall_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -405,7 +405,7 @@ static void open_dumpfile(vpiHandle callh)
       }
 }
 
-static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpfile_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -439,14 +439,14 @@ static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpflush_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpflush_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       if (dump_file) fstWriterFlushContext(dump_file);
 
       return 0;
 }
 
-static PLI_INT32 sys_dumplimit_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dumplimit_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -716,7 +716,7 @@ static int draw_scope(vpiHandle item, vpiHandle callh)
       return depth;
 }
 
-static PLI_INT32 sys_dumpvars_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpvars_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_icarus.c b/vpi/sys_icarus.c
index b4ab93f95..5d6d61f12 100644
--- a/vpi/sys_icarus.c
+++ b/vpi/sys_icarus.c
@@ -19,7 +19,7 @@
 #include "sys_priv.h"
 #include <assert.h>
 
-static PLI_INT32 finish_and_return_calltf(PLI_BYTE8* name)
+static PLI_INT32 finish_and_return_calltf(ICARUS_VPI_CONST PLI_BYTE8* name)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -41,7 +41,7 @@ static PLI_INT32 finish_and_return_calltf(PLI_BYTE8* name)
     return 0;
 }
 
-static PLI_INT32 task_not_implemented_compiletf(PLI_BYTE8* name)
+static PLI_INT32 task_not_implemented_compiletf(ICARUS_VPI_CONST PLI_BYTE8* name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
 
@@ -56,7 +56,7 @@ static PLI_INT32 task_not_implemented_compiletf(PLI_BYTE8* name)
  * This is used to warn the user that the specified optional system
  * task/function is not available (from Annex C 1364-2005).
  */
-static PLI_INT32 missing_optional_compiletf(PLI_BYTE8* name)
+static PLI_INT32 missing_optional_compiletf(ICARUS_VPI_CONST PLI_BYTE8* name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
 
diff --git a/vpi/sys_lxt.c b/vpi/sys_lxt.c
index 6ab697ffa..5275a84b3 100644
--- a/vpi/sys_lxt.c
+++ b/vpi/sys_lxt.c
@@ -348,7 +348,7 @@ __inline__ static int install_dumpvars_callback(void)
       return 0;
 }
 
-static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpoff_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -375,7 +375,7 @@ static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpon_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -402,7 +402,7 @@ static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpall_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpall_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -460,7 +460,7 @@ static void open_dumpfile(vpiHandle callh)
       }
 }
 
-static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpfile_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -497,12 +497,12 @@ static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
 /*
  * The LXT1 format has no concept of file flushing.
  */
-static PLI_INT32 sys_dumpflush_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpflush_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       return 0;
 }
 
-static PLI_INT32 sys_dumplimit_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dumplimit_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -713,7 +713,7 @@ static int draw_scope(vpiHandle item)
       return depth;
 }
 
-static PLI_INT32 sys_dumpvars_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpvars_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_lxt2.c b/vpi/sys_lxt2.c
index 7bbec0617..282f58fb5 100644
--- a/vpi/sys_lxt2.c
+++ b/vpi/sys_lxt2.c
@@ -386,7 +386,7 @@ __inline__ static int install_dumpvars_callback(void)
       return 0;
 }
 
-static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpoff_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -413,7 +413,7 @@ static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpon_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -440,7 +440,7 @@ static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpall_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpall_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -516,7 +516,7 @@ static void open_dumpfile(vpiHandle callh)
       }
 }
 
-static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpfile_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -557,14 +557,14 @@ static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
  * writes checkpoints out, but this makes it happen at a specific
  * time.
  */
-static PLI_INT32 sys_dumpflush_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpflush_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       if (dump_file) vcd_work_flush();
 
       return 0;
 }
 
-static PLI_INT32 sys_dumplimit_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dumplimit_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -768,7 +768,7 @@ static int draw_scope(vpiHandle item)
       return depth;
 }
 
-static PLI_INT32 sys_dumpvars_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpvars_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_plusargs.c b/vpi/sys_plusargs.c
index 5d0c4aca4..5b77483b9 100644
--- a/vpi/sys_plusargs.c
+++ b/vpi/sys_plusargs.c
@@ -27,7 +27,7 @@
  * passed to the $test$plusargs. If there is a simulator argument that
  * is like this argument, then return true. Otherwise return false.
  */
-static PLI_INT32 sys_test_plusargs_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_test_plusargs_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_value val;
       s_vpi_vlog_info info;
@@ -70,7 +70,7 @@ static PLI_INT32 sys_test_plusargs_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_value_plusargs_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_value_plusargs_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -128,7 +128,7 @@ static PLI_INT32 sys_value_plusargs_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_value_plusargs_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_value_plusargs_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_vlog_info info;
       s_vpi_value fmt;
diff --git a/vpi/sys_priv.c b/vpi/sys_priv.c
index a21af244f..131f3a060 100644
--- a/vpi/sys_priv.c
+++ b/vpi/sys_priv.c
@@ -234,7 +234,7 @@ vpiHandle sys_func_module(vpiHandle obj)
  */
 
 /* For system tasks/functions that do not take an argument. */
-PLI_INT32 sys_no_arg_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_no_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -261,7 +261,7 @@ PLI_INT32 sys_no_arg_compiletf(PLI_BYTE8 *name)
 }
 
 /* For system tasks/functions that take a single numeric argument. */
-PLI_INT32 sys_one_numeric_arg_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_one_numeric_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -289,7 +289,7 @@ PLI_INT32 sys_one_numeric_arg_compiletf(PLI_BYTE8 *name)
 }
 
 /* For system tasks/functions that take a single optional numeric argument. */
-PLI_INT32 sys_one_opt_numeric_arg_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_one_opt_numeric_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -311,7 +311,7 @@ PLI_INT32 sys_one_opt_numeric_arg_compiletf(PLI_BYTE8 *name)
 }
 
 /* For system tasks/functions that take two numeric arguments. */
-PLI_INT32 sys_two_numeric_args_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_two_numeric_args_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -356,7 +356,7 @@ PLI_INT32 sys_two_numeric_args_compiletf(PLI_BYTE8 *name)
 }
 
 /* For system tasks/functions that take a single string argument. */
-PLI_INT32 sys_one_string_arg_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_one_string_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_priv.h b/vpi/sys_priv.h
index d375a2ae9..d501040a5 100644
--- a/vpi/sys_priv.h
+++ b/vpi/sys_priv.h
@@ -59,10 +59,10 @@ extern vpiHandle sys_func_module(vpiHandle obj);
 /*
  * The standard compiletf routines.
  */
-extern PLI_INT32 sys_no_arg_compiletf(PLI_BYTE8 *name);
-extern PLI_INT32 sys_one_numeric_arg_compiletf(PLI_BYTE8 *name);
-extern PLI_INT32 sys_one_opt_numeric_arg_compiletf(PLI_BYTE8 *name);
-extern PLI_INT32 sys_two_numeric_args_compiletf(PLI_BYTE8 *name);
-extern PLI_INT32 sys_one_string_arg_compiletf(PLI_BYTE8 *name);
+extern PLI_INT32 sys_no_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
+extern PLI_INT32 sys_one_numeric_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
+extern PLI_INT32 sys_one_opt_numeric_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
+extern PLI_INT32 sys_two_numeric_args_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
+extern PLI_INT32 sys_one_string_arg_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
 
 #endif
diff --git a/vpi/sys_random.c b/vpi/sys_random.c
index f23d64b09..8fc343fba 100644
--- a/vpi/sys_random.c
+++ b/vpi/sys_random.c
@@ -388,7 +388,7 @@ static unsigned is_seed_obj(vpiHandle obj, vpiHandle callh, char *name)
       return rtn;
 }
 
-static PLI_INT32 sys_rand_two_args_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_rand_two_args_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -432,7 +432,7 @@ static PLI_INT32 sys_rand_two_args_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-PLI_INT32 sys_rand_three_args_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_rand_three_args_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -490,7 +490,7 @@ PLI_INT32 sys_rand_three_args_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-PLI_INT32 sys_random_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_random_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -507,7 +507,7 @@ PLI_INT32 sys_random_compiletf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_random_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_random_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed = 0;
       s_vpi_value val;
@@ -539,7 +539,7 @@ static PLI_INT32 sys_random_calltf(PLI_BYTE8 *name)
 }
 
 /* From System Verilog 3.1a. */
-static PLI_INT32 sys_urandom_range_compiletf(PLI_BYTE8 *name)
+static PLI_INT32 sys_urandom_range_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -589,7 +589,7 @@ static unsigned long urandom(long *seed, unsigned long max, unsigned long min)
 }
 
 /* From System Verilog 3.1a. */
-static PLI_INT32 sys_urandom_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_urandom_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed = 0;
       s_vpi_value val;
@@ -625,7 +625,7 @@ static PLI_INT32 sys_urandom_calltf(PLI_BYTE8 *name)
 }
 
 /* From System Verilog 3.1a. */
-static PLI_INT32 sys_urandom_range_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_urandom_range_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, maxval, minval;
       s_vpi_value val;
@@ -658,7 +658,7 @@ static PLI_INT32 sys_urandom_range_calltf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_dist_uniform_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dist_uniform_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed, start, end;
       s_vpi_value val;
@@ -693,7 +693,7 @@ static PLI_INT32 sys_dist_uniform_calltf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_dist_normal_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dist_normal_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed, mean, sd;
       s_vpi_value val;
@@ -728,7 +728,7 @@ static PLI_INT32 sys_dist_normal_calltf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_dist_exponential_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dist_exponential_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed, mean;
       s_vpi_value val;
@@ -759,7 +759,7 @@ static PLI_INT32 sys_dist_exponential_calltf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_dist_poisson_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dist_poisson_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed, mean;
       s_vpi_value val;
@@ -790,7 +790,7 @@ static PLI_INT32 sys_dist_poisson_calltf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_dist_chi_square_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dist_chi_square_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed, df;
       s_vpi_value val;
@@ -821,7 +821,7 @@ static PLI_INT32 sys_dist_chi_square_calltf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_dist_t_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dist_t_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed, df;
       s_vpi_value val;
@@ -852,7 +852,7 @@ static PLI_INT32 sys_dist_t_calltf(PLI_BYTE8 *name)
       return 0;
 }
 
-static PLI_INT32 sys_dist_erlang_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dist_erlang_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh, argv, seed, k, mean;
       s_vpi_value val;
diff --git a/vpi/sys_random.h b/vpi/sys_random.h
index ca94b9c7d..b03bb3a11 100644
--- a/vpi/sys_random.h
+++ b/vpi/sys_random.h
@@ -24,7 +24,7 @@
 /*
  * Common compiletf routines for the different random implementations.
  */
-extern PLI_INT32 sys_rand_three_args_compiletf(PLI_BYTE8 *name);
-extern PLI_INT32 sys_random_compiletf(PLI_BYTE8 *name);
+extern PLI_INT32 sys_rand_three_args_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
+extern PLI_INT32 sys_random_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
 
 #endif
diff --git a/vpi/sys_random_mti.c b/vpi/sys_random_mti.c
index 99d57f35a..c57fc7663 100644
--- a/vpi/sys_random_mti.c
+++ b/vpi/sys_random_mti.c
@@ -56,7 +56,7 @@ static long mti_dist_uniform(long*seed, long start, long end)
       }
 }
 
-static PLI_INT32 sys_mti_dist_uniform_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_mti_dist_uniform_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh, argv, seed, start, end;
       s_vpi_value val;
@@ -91,7 +91,7 @@ static PLI_INT32 sys_mti_dist_uniform_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_mti_random_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_mti_random_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh, argv, seed = 0;
       s_vpi_value val;
diff --git a/vpi/sys_readmem.c b/vpi/sys_readmem.c
index 0038ab3ee..309e73d31 100644
--- a/vpi/sys_readmem.c
+++ b/vpi/sys_readmem.c
@@ -186,7 +186,7 @@ static int process_params(vpiHandle mitem,
       return 0;
 }
 
-static PLI_INT32 sys_mem_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_mem_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -255,7 +255,7 @@ static PLI_INT32 sys_mem_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_readmem_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_readmem_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       int code, wwid, addr;
       FILE*file;
@@ -417,7 +417,7 @@ static PLI_INT32 free_readmempath(p_cb_data cb_data)
       return 0;
 }
 
-static PLI_INT32 sys_readmempath_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_readmempath_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -501,7 +501,7 @@ static PLI_INT32 sys_readmempath_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_writemem_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_writemem_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       int addr;
       FILE*file;
diff --git a/vpi/sys_scanf.c b/vpi/sys_scanf.c
index 30c227385..220ebfe43 100644
--- a/vpi/sys_scanf.c
+++ b/vpi/sys_scanf.c
@@ -605,7 +605,7 @@ static int sys_check_args(vpiHandle callh, vpiHandle argv, PLI_BYTE8 *name)
       return rtn;
 }
 
-static PLI_INT32 sys_fscanf_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_fscanf_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -633,7 +633,7 @@ static PLI_INT32 sys_fscanf_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_fscanf_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_fscanf_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -665,7 +665,7 @@ static PLI_INT32 sys_fscanf_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_sscanf_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_sscanf_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -703,7 +703,7 @@ static PLI_INT32 sys_sscanf_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_sscanf_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_sscanf_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_sdf.c b/vpi/sys_sdf.c
index 0c8c02760..37465a913 100644
--- a/vpi/sys_sdf.c
+++ b/vpi/sys_sdf.c
@@ -236,7 +236,7 @@ static void check_command_line_args(void)
       sdf_command_line_done = 1;
 }
 
-static PLI_INT32 sys_sdf_annotate_compiletf(PLI_BYTE8*name)
+static PLI_INT32 sys_sdf_annotate_compiletf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall,0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -282,7 +282,7 @@ static PLI_INT32 sys_sdf_annotate_compiletf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_sdf_annotate_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_sdf_annotate_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_time.c b/vpi/sys_time.c
index d3d69db0f..65f361600 100644
--- a/vpi/sys_time.c
+++ b/vpi/sys_time.c
@@ -22,7 +22,7 @@
 #include <math.h>
 #include <assert.h>
 
-static PLI_INT32 sys_time_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_time_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_value val;
       s_vpi_time  now;
@@ -78,7 +78,7 @@ static PLI_INT32 sys_time_calltf(PLI_BYTE8*name)
 }
 
 /* This also supports $abstime() from VAMS-2.3. */
-static PLI_INT32 sys_realtime_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_realtime_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_value val;
       s_vpi_time  now;
diff --git a/vpi/sys_vcd.c b/vpi/sys_vcd.c
index edcd2ee1d..bf84ecad4 100644
--- a/vpi/sys_vcd.c
+++ b/vpi/sys_vcd.c
@@ -308,7 +308,7 @@ __inline__ static int install_dumpvars_callback(void)
       return 0;
 }
 
-static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpoff_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -336,7 +336,7 @@ static PLI_INT32 sys_dumpoff_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpon_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -364,7 +364,7 @@ static PLI_INT32 sys_dumpon_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpall_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpall_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       s_vpi_time now;
       PLI_UINT64 now64;
@@ -434,7 +434,7 @@ static void open_dumpfile(vpiHandle callh)
       }
 }
 
-static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpfile_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -468,14 +468,14 @@ static PLI_INT32 sys_dumpfile_calltf(PLI_BYTE8*name)
       return 0;
 }
 
-static PLI_INT32 sys_dumpflush_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpflush_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       if (dump_file) fflush(dump_file);
 
       return 0;
 }
 
-static PLI_INT32 sys_dumplimit_calltf(PLI_BYTE8 *name)
+static PLI_INT32 sys_dumplimit_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -736,7 +736,7 @@ static int draw_scope(vpiHandle item, vpiHandle callh)
       return depth;
 }
 
-static PLI_INT32 sys_dumpvars_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpvars_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/sys_vcdoff.c b/vpi/sys_vcdoff.c
index b98d283ed..96d41321f 100644
--- a/vpi/sys_vcdoff.c
+++ b/vpi/sys_vcdoff.c
@@ -33,12 +33,12 @@
 
 static int dump_flag = 0;
 
-static PLI_INT32 sys_dummy_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dummy_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       return 0;
 }
 
-static PLI_INT32 sys_dumpvars_calltf(PLI_BYTE8*name)
+static PLI_INT32 sys_dumpvars_calltf(ICARUS_VPI_CONST PLI_BYTE8*name)
 {
       if (dump_flag == 0) {
 	    vpi_printf("VCD info: dumping is suppressed.\n");
diff --git a/vpi/v2005_math.c b/vpi/v2005_math.c
index 26ad07d61..e37853bcd 100644
--- a/vpi/v2005_math.c
+++ b/vpi/v2005_math.c
@@ -159,7 +159,7 @@ vpiHandle va_process_argument(vpiHandle callh, const char *name,
 /*
  * Routine to check all the single argument math functions.
  */
-static PLI_INT32 va_single_argument_compiletf(PLI_BYTE8 *ud)
+static PLI_INT32 va_single_argument_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh, argv, arg;
     t_single_data *data;
@@ -215,7 +215,7 @@ static PLI_INT32 va_single_argument_compiletf(PLI_BYTE8 *ud)
 /*
  * Routine to implement the single argument math functions.
  */
-static PLI_INT32 va_single_argument_calltf(PLI_BYTE8 *ud)
+static PLI_INT32 va_single_argument_calltf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     s_vpi_value val;
@@ -241,7 +241,7 @@ static PLI_INT32 va_single_argument_calltf(PLI_BYTE8 *ud)
 /*
  * Routine to check all the double argument math functions.
  */
-static PLI_INT32 va_double_argument_compiletf(PLI_BYTE8 *ud)
+static PLI_INT32 va_double_argument_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh, argv, arg;
     t_double_data *data;
@@ -304,7 +304,7 @@ static PLI_INT32 va_double_argument_compiletf(PLI_BYTE8 *ud)
 /*
  * Routine to implement the double argument math functions.
  */
-static PLI_INT32 va_double_argument_calltf(PLI_BYTE8 *ud)
+static PLI_INT32 va_double_argument_calltf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     s_vpi_value val;
diff --git a/vpi/va_math.c b/vpi/va_math.c
index 28c60afe4..40f2b3196 100644
--- a/vpi/va_math.c
+++ b/vpi/va_math.c
@@ -186,7 +186,7 @@ vpiHandle va_process_argument(vpiHandle callh, const char *name,
 /*
  * Routine to check all the single argument math functions.
  */
-static PLI_INT32 va_single_argument_compiletf(PLI_BYTE8 *ud)
+static PLI_INT32 va_single_argument_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh, argv, arg;
     t_single_data *data;
@@ -242,7 +242,7 @@ static PLI_INT32 va_single_argument_compiletf(PLI_BYTE8 *ud)
 /*
  * Routine to implement the single argument math functions.
  */
-static PLI_INT32 va_single_argument_calltf(PLI_BYTE8 *ud)
+static PLI_INT32 va_single_argument_calltf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     s_vpi_value val;
@@ -268,7 +268,7 @@ static PLI_INT32 va_single_argument_calltf(PLI_BYTE8 *ud)
 /*
  * Routine to check all the double argument math functions.
  */
-static PLI_INT32 va_double_argument_compiletf(PLI_BYTE8 *ud)
+static PLI_INT32 va_double_argument_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh, argv, arg;
     t_double_data *data;
@@ -331,7 +331,7 @@ static PLI_INT32 va_double_argument_compiletf(PLI_BYTE8 *ud)
 /*
  * Routine to implement the double argument math functions.
  */
-static PLI_INT32 va_double_argument_calltf(PLI_BYTE8 *ud)
+static PLI_INT32 va_double_argument_calltf(ICARUS_VPI_CONST PLI_BYTE8 *ud)
 {
     vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
     s_vpi_value val;
diff --git a/vpi/vams_simparam.c b/vpi/vams_simparam.c
index 3af29e82d..ab63ae636 100644
--- a/vpi/vams_simparam.c
+++ b/vpi/vams_simparam.c
@@ -31,7 +31,7 @@
 /*
  * Check that the routines are called with the correct arguments.
  */
-static PLI_INT32 simparam_compiletf(PLI_BYTE8 *name_ext)
+static PLI_INT32 simparam_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name_ext)
 {
       vpiHandle callh, argv, arg;
 
@@ -104,7 +104,7 @@ static PLI_INT32 simparam_compiletf(PLI_BYTE8 *name_ext)
       return 0;
 }
 
-static PLI_INT32 simparam_calltf(PLI_BYTE8 *name_ext)
+static PLI_INT32 simparam_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name_ext)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
@@ -179,7 +179,7 @@ static PLI_INT32 simparam_calltf(PLI_BYTE8 *name_ext)
       return 0;
 }
 
-static PLI_INT32 simparam_str_calltf(PLI_BYTE8 *name_ext)
+static PLI_INT32 simparam_str_calltf(ICARUS_VPI_CONST PLI_BYTE8 *name_ext)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/vcd_priv.c b/vpi/vcd_priv.c
index 3817c9363..9a900294c 100644
--- a/vpi/vcd_priv.c
+++ b/vpi/vcd_priv.c
@@ -137,7 +137,7 @@ void vcd_names_sort(struct vcd_names_list_s*tab)
  */
 
 /* $dumpvars takes a variety of arguments. */
-PLI_INT32 sys_dumpvars_compiletf(PLI_BYTE8 *name)
+PLI_INT32 sys_dumpvars_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name)
 {
       vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
       vpiHandle argv = vpi_iterate(vpiArgument, callh);
diff --git a/vpi/vcd_priv.h b/vpi/vcd_priv.h
index 672cf602c..2772dadfb 100644
--- a/vpi/vcd_priv.h
+++ b/vpi/vcd_priv.h
@@ -127,7 +127,7 @@ EXTERN void vcd_work_emit_double(struct lxt2_wr_symbol*sym, double val);
 EXTERN void vcd_work_emit_bits(struct lxt2_wr_symbol*sym, const char*bits);
 
 /* The compiletf routines are common for the VCD, LXT and LXT2 dumpers. */
-EXTERN PLI_INT32 sys_dumpvars_compiletf(PLI_BYTE8 *name);
+EXTERN PLI_INT32 sys_dumpvars_compiletf(ICARUS_VPI_CONST PLI_BYTE8 *name);
 
 #undef EXTERN
 
diff --git a/vpi_user.h b/vpi_user.h
index f7011f9aa..abe25f8db 100644
--- a/vpi_user.h
+++ b/vpi_user.h
@@ -45,6 +45,7 @@ EXTERN_C_START
 # include  <stdio.h>
 # include  "_pli_types.h"
 
+#define ICARUS_VPI_CONST
 typedef struct __vpiHandle *vpiHandle;
 
 /*
@@ -55,10 +56,10 @@ typedef struct t_vpi_systf_data {
       PLI_INT32 type;
       PLI_INT32 sysfunctype;
       const char *tfname;
-      PLI_INT32 (*calltf)   (PLI_BYTE8*);
-      PLI_INT32 (*compiletf)(PLI_BYTE8*);
+      PLI_INT32 (*calltf)   (ICARUS_VPI_CONST PLI_BYTE8*);
+      PLI_INT32 (*compiletf)(ICARUS_VPI_CONST PLI_BYTE8*);
       PLI_INT32 (*sizetf)   (PLI_BYTE8*);
-      PLI_BYTE8 *user_data;
+      ICARUS_VPI_CONST PLI_BYTE8 *user_data;
 } s_vpi_systf_data, *p_vpi_systf_data;
 
 /* The type in the above structure can have one of the following