diff --git a/vpi/sys_clog2.c b/vpi/sys_clog2.c
index e4921152a..bd6517837 100644
--- a/vpi/sys_clog2.c
+++ b/vpi/sys_clog2.c
@@ -19,7 +19,7 @@
 #include <assert.h>
 #include <math.h>
 #include <string.h>
-#include <vpi_user.h>
+#include "vpi_user.h"
 
 /*
  * This routine returns 1 if the argument supports has a numeric value,
diff --git a/vpi/sys_convert.c b/vpi/sys_convert.c
index efcf5bda9..4b296ff61 100644
--- a/vpi/sys_convert.c
+++ b/vpi/sys_convert.c
@@ -17,8 +17,6 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-# include  "vpi_config.h"
-# include  "vpi_user.h"
 # include  "sys_priv.h"
 # include  <stdio.h>
 # include  <string.h>
diff --git a/vpi/sys_deposit.c b/vpi/sys_deposit.c
index f7b7a312c..b78acb624 100644
--- a/vpi/sys_deposit.c
+++ b/vpi/sys_deposit.c
@@ -18,8 +18,6 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-# include  "vpi_config.h"
-# include  "vpi_user.h"
 # include  "sys_priv.h"
 # include  <assert.h>
 # include  <string.h>
diff --git a/vpi/sys_display.c b/vpi/sys_display.c
index f56f5fa4a..e728eb84d 100644
--- a/vpi/sys_display.c
+++ b/vpi/sys_display.c
@@ -17,9 +17,6 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-# include "vpi_config.h"
-
-# include  "vpi_user.h"
 # include  "sys_priv.h"
 # include  <assert.h>
 # include  <string.h>
diff --git a/vpi/sys_fileio.c b/vpi/sys_fileio.c
index 6ff30cbbb..24df435cf 100644
--- a/vpi/sys_fileio.c
+++ b/vpi/sys_fileio.c
@@ -17,7 +17,6 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-# include  "vpi_user.h"
 # include  "sys_priv.h"
 # include  <assert.h>
 # include  <ctype.h>
diff --git a/vpi/sys_finish.c b/vpi/sys_finish.c
index 998c41724..0a555c7e3 100644
--- a/vpi/sys_finish.c
+++ b/vpi/sys_finish.c
@@ -17,8 +17,6 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-#include "vpi_config.h"
-#include "vpi_user.h"
 #include "sys_priv.h"
 #include <string.h>
 
diff --git a/vpi/sys_icarus.c b/vpi/sys_icarus.c
index 7c194ae93..b4ab93f95 100644
--- a/vpi/sys_icarus.c
+++ b/vpi/sys_icarus.c
@@ -16,9 +16,8 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <assert.h>
-#include <vpi_user.h>
 #include "sys_priv.h"
+#include <assert.h>
 
 static PLI_INT32 finish_and_return_calltf(PLI_BYTE8* name)
 {
diff --git a/vpi/sys_lxt.c b/vpi/sys_lxt.c
index 3fff806f0..ca20de692 100644
--- a/vpi/sys_lxt.c
+++ b/vpi/sys_lxt.c
@@ -17,10 +17,9 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-/* The vpi_config.h include must be before the lxt_write.h include! */
-# include "vpi_config.h"
-# include "lxt_write.h"
+/* The sys_priv.h include must be before the lxt_write.h include! */
 # include "sys_priv.h"
+# include "lxt_write.h"
 # include "vcd_priv.h"
 
 /*
@@ -28,7 +27,6 @@
  * funcitons.
  */
 
-# include  "vpi_user.h"
 # include  <stdio.h>
 # include  <stdlib.h>
 # include  <string.h>
diff --git a/vpi/sys_lxt2.c b/vpi/sys_lxt2.c
index fd4e7acda..2fcd7d9cf 100644
--- a/vpi/sys_lxt2.c
+++ b/vpi/sys_lxt2.c
@@ -17,10 +17,9 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-/* The vpi_config.h include must be before the lxt2_write.h include! */
-# include "vpi_config.h"
-# include "lxt2_write.h"
+/* The sys_priv.h include must be before the lxt2_write.h include! */
 # include "sys_priv.h"
+# include "lxt2_write.h"
 # include "vcd_priv.h"
 
 /*
@@ -28,7 +27,6 @@
  * funcitons.
  */
 
-# include  "vpi_user.h"
 # include  <stdio.h>
 # include  <stdlib.h>
 # include  <string.h>
diff --git a/vpi/sys_plusargs.c b/vpi/sys_plusargs.c
index 5c1257b85..5d0c4aca4 100644
--- a/vpi/sys_plusargs.c
+++ b/vpi/sys_plusargs.c
@@ -18,7 +18,6 @@
  */
 
 # include  "sys_priv.h"
-# include  <vpi_user.h>
 # include  <string.h>
 # include  <stdlib.h>
 # include  <assert.h>
diff --git a/vpi/sys_priv.c b/vpi/sys_priv.c
index c0d13f5c8..a120b17a0 100644
--- a/vpi/sys_priv.c
+++ b/vpi/sys_priv.c
@@ -17,11 +17,11 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
+#include "sys_priv.h"
 #include <assert.h>
 #include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
-#include "sys_priv.h"
 
 PLI_UINT64 timerec_to_time64(const struct t_vpi_time*time)
 {
diff --git a/vpi/sys_random.c b/vpi/sys_random.c
index 05c4ddaee..f23d64b09 100644
--- a/vpi/sys_random.c
+++ b/vpi/sys_random.c
@@ -20,7 +20,6 @@
 # include "sys_priv.h"
 # include "sys_random.h"
 
-# include  <vpi_user.h>
 # include  <assert.h>
 # include  <stdlib.h>
 # include  <math.h>
diff --git a/vpi/sys_random_mti.c b/vpi/sys_random_mti.c
index 30d7dd341..99d57f35a 100644
--- a/vpi/sys_random_mti.c
+++ b/vpi/sys_random_mti.c
@@ -20,7 +20,6 @@
 # include "sys_priv.h"
 # include "sys_random.h"
 
-# include  <vpi_user.h>
 # include  <assert.h>
 # include  <stdlib.h>
 # include  <math.h>
diff --git a/vpi/sys_readmem.c b/vpi/sys_readmem.c
index ef1a761ae..fc95d2cd7 100644
--- a/vpi/sys_readmem.c
+++ b/vpi/sys_readmem.c
@@ -17,9 +17,6 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-# include "vpi_config.h"
-
-# include  "vpi_user.h"
 # include  "sys_priv.h"
 # include  <ctype.h>
 # include  <string.h>
diff --git a/vpi/sys_scanf.c b/vpi/sys_scanf.c
index 0c0d10b19..e89901d2a 100644
--- a/vpi/sys_scanf.c
+++ b/vpi/sys_scanf.c
@@ -21,7 +21,6 @@
 # define _ISOC99_SOURCE 1
 # define _SVID_SOURCE 1
 
-# include  "vpi_user.h"
 # include  "sys_priv.h"
 # include  <ctype.h>
 # include  <errno.h>
diff --git a/vpi/sys_sdf.c b/vpi/sys_sdf.c
index 622cc3468..de5db92c7 100644
--- a/vpi/sys_sdf.c
+++ b/vpi/sys_sdf.c
@@ -17,11 +17,8 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-# include "vpi_config.h"
-
-# include  "vpi_user.h"
-# include  "sdf_priv.h"
 # include  "sys_priv.h"
+# include  "sdf_priv.h"
 # include  <stdlib.h>
 # include  <string.h>
 # include  <assert.h>
diff --git a/vpi/sys_time.c b/vpi/sys_time.c
index 7ae40f09f..eca5325cb 100644
--- a/vpi/sys_time.c
+++ b/vpi/sys_time.c
@@ -17,13 +17,10 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-#include "vpi_config.h"
-
-#include "vpi_user.h"
+#include "sys_priv.h"
 #include <string.h>
 #include <math.h>
 #include <assert.h>
-#include <sys_priv.h>
 
 static PLI_INT32 sys_time_calltf(PLI_BYTE8*name)
 {
diff --git a/vpi/sys_vcd.c b/vpi/sys_vcd.c
index bf9e9580e..559445cdb 100644
--- a/vpi/sys_vcd.c
+++ b/vpi/sys_vcd.c
@@ -25,7 +25,6 @@
  * funcitons.
  */
 
-# include  "vpi_user.h"
 # include  <stdio.h>
 # include  <stdlib.h>
 # include  <string.h>
diff --git a/vpi/sys_vcdoff.c b/vpi/sys_vcdoff.c
index eb30eedac..d59801005 100644
--- a/vpi/sys_vcdoff.c
+++ b/vpi/sys_vcdoff.c
@@ -23,7 +23,6 @@
  * This file contains do nothing stubs of all the VCD routines.
  */
 
-# include  "vpi_user.h"
 # include  <stdio.h>
 # include  <stdlib.h>
 # include  <string.h>
diff --git a/vpi/v2005_math.c b/vpi/v2005_math.c
index 4183dd7d5..26ad07d61 100644
--- a/vpi/v2005_math.c
+++ b/vpi/v2005_math.c
@@ -24,7 +24,7 @@
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>
-#include <vpi_user.h>
+#include "vpi_user.h"
 
 /* Single argument functions. */
 typedef struct s_single_data {
diff --git a/vpi/va_math.c b/vpi/va_math.c
index 08af411e8..28c60afe4 100644
--- a/vpi/va_math.c
+++ b/vpi/va_math.c
@@ -24,7 +24,7 @@
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>
-#include <vpi_user.h>
+#include "vpi_user.h"
 
 /*
  * Compile time options: (set in the Makefile.)
diff --git a/vpi/vams_simparam.c b/vpi/vams_simparam.c
index 11779a8c1..e48e061ba 100644
--- a/vpi/vams_simparam.c
+++ b/vpi/vams_simparam.c
@@ -16,6 +16,7 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include "sys_priv.h"
 #include <assert.h>
 #ifdef HAVE_MALLOC_H
 # include <malloc.h>
@@ -24,8 +25,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <vpi_user.h>
-#include "sys_priv.h"
 #include "version_base.h"
 
 /* Once we have real string objects replace this with a dynamic string. */
diff --git a/vpi/vcd_priv.c b/vpi/vcd_priv.c
index 104256022..c44879fd2 100644
--- a/vpi/vcd_priv.c
+++ b/vpi/vcd_priv.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
-#include  "vpi_config.h"
+#include  "sys_priv.h"
 #include  "vcd_priv.h"
 #include  <stdio.h>
 #include  <stdlib.h>
@@ -28,7 +28,6 @@
 #endif
 #include  <ctype.h>
 #include  "stringheap.h"
-#include  <sys_priv.h>
 
 int is_escaped_id(const char *name)
 {