diff --git a/Documentation/usage/command_line_flags.rst b/Documentation/usage/command_line_flags.rst
index 302021957..a3d9abfbf 100644
--- a/Documentation/usage/command_line_flags.rst
+++ b/Documentation/usage/command_line_flags.rst
@@ -342,9 +342,9 @@ These flags affect the general behavior of the compiler.
 
   * select-range
 
-    This enables warnings for constant out-of-bound selects. This includes
-    partial or fully out-of-bound select as well as a select containing a 'bx
-    or 'bz in the index.
+    This enables warnings for constant and runtime out-of-bound selects. This
+    includes partial or fully out-of-bound select as well as a select containing
+    a 'bx or 'bz in the index.
 
   * timescale
 
diff --git a/driver/iverilog.man.in b/driver/iverilog.man.in
index b5f4d1360..259023ab2 100644
--- a/driver/iverilog.man.in
+++ b/driver/iverilog.man.in
@@ -421,8 +421,8 @@ will generate a warning.
 
 .TP 8
 .B select-range
-This enables warnings for constant out of bound selects. This includes
-partial or fully out of bound selects as well as a select containing
+This enables warnings for constant and runtime out-of-bound selects. This
+includes partial or fully out-of-bound select as well as a select containing
 a 'bx or 'bz in the index.
 
 .TP 8
diff --git a/ivtest/gold/unpacked_array_oob_write_nowarn-vvp-stdout.gold b/ivtest/gold/unpacked_array_oob_write_nowarn-vvp-stdout.gold
new file mode 100644
index 000000000..53cdf1e93
--- /dev/null
+++ b/ivtest/gold/unpacked_array_oob_write_nowarn-vvp-stdout.gold
@@ -0,0 +1 @@
+PASSED
diff --git a/ivtest/gold/unpacked_array_oob_write_warn-vvp-stderr.gold b/ivtest/gold/unpacked_array_oob_write_warn-vvp-stderr.gold
new file mode 100644
index 000000000..2fac554ca
--- /dev/null
+++ b/ivtest/gold/unpacked_array_oob_write_warn-vvp-stderr.gold
@@ -0,0 +1,7 @@
+ivltests/unpacked_array_oob_write_warn.v:21: Warning: out-of-bounds unpacked array write index 4 for 'a[0:3]'; write ignored.
+ivltests/unpacked_array_oob_write_warn.v:24: Warning: out-of-bounds unpacked array write index -1 for 'a[0:3]'; write ignored.
+ivltests/unpacked_array_oob_write_warn.v:27: Warning: out-of-bounds unpacked array write index 5 for 'a[0:3]'; write ignored.
+ivltests/unpacked_array_oob_write_warn.v:30: Warning: out-of-bounds unpacked array write index 3 for 'r[0:1]'; write ignored.
+ivltests/unpacked_array_oob_write_warn.v:33: Warning: undefined unpacked array write index for 'a[0:3]'; write ignored.
+ivltests/unpacked_array_oob_write_warn.v:36: Warning: undefined unpacked array write index for 'a[0:3]'; write ignored.
+ivltests/unpacked_array_oob_write_warn.v:39: Warning: undefined unpacked array write index for 'r[0:1]'; write ignored.
diff --git a/ivtest/gold/unpacked_array_oob_write_warn-vvp-stdout.gold b/ivtest/gold/unpacked_array_oob_write_warn-vvp-stdout.gold
new file mode 100644
index 000000000..53cdf1e93
--- /dev/null
+++ b/ivtest/gold/unpacked_array_oob_write_warn-vvp-stdout.gold
@@ -0,0 +1 @@
+PASSED
diff --git a/ivtest/ivltests/unpacked_array_oob_write_warn.v b/ivtest/ivltests/unpacked_array_oob_write_warn.v
new file mode 100644
index 000000000..babc99bf4
--- /dev/null
+++ b/ivtest/ivltests/unpacked_array_oob_write_warn.v
@@ -0,0 +1,57 @@
+module main;
+  logic [7:0] a [0:3];
+  real r [0:1];
+  integer idx;
+  integer errors;
+
+  initial begin
+    errors = 0;
+
+    a[0] = 8'h11;
+    a[1] = 8'h22;
+    a[2] = 8'h33;
+    a[3] = 8'h44;
+    r[0] = 1.25;
+    r[1] = 2.50;
+
+    idx = 2;
+    a[idx] = 8'haa;
+
+    idx = 4;
+    a[idx] = 8'hff;
+
+    idx = -1;
+    a[idx] <= 8'hee;
+
+    idx = 5;
+    repeat (2) a[idx] = 8'h77;
+
+    idx = 3;
+    r[idx] <= 9.50;
+
+    idx = 'bx;
+    a[idx] = 8'h66;
+
+    idx = 'bz;
+    a[idx] <= 8'h55;
+
+    idx = 'bx;
+    r[idx] = 7.25;
+
+    #1;
+
+    if (a[0] !== 8'h11) errors = errors + 1;
+    if (a[1] !== 8'h22) errors = errors + 1;
+    if (a[2] !== 8'haa) errors = errors + 1;
+    if (a[3] !== 8'h44) errors = errors + 1;
+    if (r[0] != 1.25) errors = errors + 1;
+    if (r[1] != 2.50) errors = errors + 1;
+
+    if (errors) begin
+      $display("FAILED");
+      $finish(1);
+    end
+
+    $display("PASSED");
+  end
+endmodule
diff --git a/ivtest/regress-vvp.list b/ivtest/regress-vvp.list
index 2475c4d3a..c3ef00a1d 100644
--- a/ivtest/regress-vvp.list
+++ b/ivtest/regress-vvp.list
@@ -380,6 +380,8 @@ test_va_math			vvp_tests/test_va_math.json
 test_vams_math			vvp_tests/test_vams_math.json
 timing_check_syntax		vvp_tests/timing_check_syntax.json
 timing_check_delayed_signals	vvp_tests/timing_check_delayed_signals.json
+unpacked_array_oob_write_nowarn	vvp_tests/unpacked_array_oob_write_nowarn.json
+unpacked_array_oob_write_warn	vvp_tests/unpacked_array_oob_write_warn.json
 uwire_fail2			vvp_tests/uwire_fail2.json
 uwire_fail3			vvp_tests/uwire_fail3.json
 value_range1			vvp_tests/value_range1.json
diff --git a/ivtest/vvp_tests/unpacked_array_oob_write_nowarn.json b/ivtest/vvp_tests/unpacked_array_oob_write_nowarn.json
new file mode 100644
index 000000000..528a0b0b2
--- /dev/null
+++ b/ivtest/vvp_tests/unpacked_array_oob_write_nowarn.json
@@ -0,0 +1,6 @@
+{
+    "type"          : "normal",
+    "source"        : "unpacked_array_oob_write_warn.v",
+    "iverilog-args" : [ "-g2005-sv", "-pfileline=1" ],
+    "gold"          : "unpacked_array_oob_write_nowarn"
+}
diff --git a/ivtest/vvp_tests/unpacked_array_oob_write_warn.json b/ivtest/vvp_tests/unpacked_array_oob_write_warn.json
new file mode 100644
index 000000000..833b78fbc
--- /dev/null
+++ b/ivtest/vvp_tests/unpacked_array_oob_write_warn.json
@@ -0,0 +1,6 @@
+{
+    "type"          : "normal",
+    "source"        : "unpacked_array_oob_write_warn.v",
+    "iverilog-args" : [ "-g2005-sv", "-Wselect-range", "-pfileline=1" ],
+    "gold"          : "unpacked_array_oob_write_warn"
+}
diff --git a/main.cc b/main.cc
index 917e006e9..0e253dc98 100644
--- a/main.cc
+++ b/main.cc
@@ -749,6 +749,8 @@ static void read_iconfig_file(const char*ipath)
 		  roots.push_back(lex_strings.make(cp));
 
 	    } else if (strcmp(buf,"warnings") == 0) {
+		  free(reinterpret_cast<void*>(const_cast<char*>(flags["warnings"])));
+		  flags["warnings"] = strdup(cp);
 		    /* Scan the warnings enable string for warning flags. */
 		  for ( ;  *cp ;  cp += 1) switch (*cp) {
 		      case 'f':
diff --git a/tgt-vvp/vvp.c b/tgt-vvp/vvp.c
index 074e8d64d..f275ef118 100644
--- a/tgt-vvp/vvp.c
+++ b/tgt-vvp/vvp.c
@@ -162,6 +162,7 @@ int target_design(ivl_design_t des)
 	 * printed for procedural statements. (e.g. -pfileline=1).
 	 * The default is no file/line information will be included. */
       const char*fileline = ivl_design_flag(des, "fileline");
+      const char*warnings = ivl_design_flag(des, "warnings");
 
       const char*debug_flags = ivl_design_flag(des, "debug_flags");
       process_debug_string(debug_flags);
@@ -210,6 +211,8 @@ int target_design(ivl_design_t des)
 
       fprintf(vvp_out, ":ivl_delay_selection \"%s\";\n",
                        ivl_design_delay_sel(des));
+      if (warnings && *warnings)
+	    fprintf(vvp_out, ":ivl_warnings \"%s\";\n", warnings);
 
       { int pre = ivl_design_time_precision(des);
 	char sign = '+';
diff --git a/tgt-vvp/vvp_process.c b/tgt-vvp/vvp_process.c
index 8382b94ab..a1bfdd9af 100644
--- a/tgt-vvp/vvp_process.c
+++ b/tgt-vvp/vvp_process.c
@@ -40,7 +40,6 @@ static void assign_to_array_r_word(ivl_signal_t lsig, ivl_expr_t word_ix,
                                    uint64_t delay,
                                    ivl_expr_t dexp, unsigned nevents)
 {
-      unsigned end_assign = transient_id++;
       int word_ix_reg = 3;
 
       /* if we have to evaluate a delay expression, evaluate word index into
@@ -54,24 +53,23 @@ static void assign_to_array_r_word(ivl_signal_t lsig, ivl_expr_t word_ix,
 	  !number_is_unknown(word_ix)) {
 	    fprintf(vvp_out, "    %%ix/load %d, %ld, 0; address\n",
 		    word_ix_reg, get_number_immediate(word_ix));
+	    fprintf(vvp_out, "    %%flag_set/imm 4, 0;\n");
       } else {
 	      /* Calculate array word index into index register 3 */
 	    draw_eval_expr_into_integer(word_ix, word_ix_reg);
-	      /* Skip assignment if word expression is not defined. */
-	    unsigned do_assign = transient_id++;
-	    fprintf(vvp_out, "    %%jmp/0 t_%u, 4;\n", do_assign);
-	    fprintf(vvp_out, "    %%pop/real 1;\n");
-	    fprintf(vvp_out, "    %%jmp t_%u;\n", end_assign);
-	    fprintf(vvp_out, "t_%u ;\n", do_assign);
       }
 
       if (dexp != 0) {
 	      /* Calculated delay... */
 	    int delay_index = allocate_word();
+	    int index_flag = allocate_flag();
+	    fprintf(vvp_out, "    %%flag_mov %d, 4;\n", index_flag);
 	    draw_eval_expr_into_integer(dexp, delay_index);
 	    fprintf(vvp_out, "    %%ix/mov 3, %d;\n", word_ix_reg);
+	    fprintf(vvp_out, "    %%flag_mov 4, %d;\n", index_flag);
 	    fprintf(vvp_out, "    %%assign/ar/d v%p, %d;\n", lsig,
 	                     delay_index);
+	    clr_flag(index_flag);
 	    clr_word(word_ix_reg);
 	    clr_word(delay_index);
       } else if (nevents != 0) {
@@ -99,7 +97,6 @@ static void assign_to_array_r_word(ivl_signal_t lsig, ivl_expr_t word_ix,
 	    }
       }
 
-      fprintf(vvp_out, "t_%u ;\n", end_assign);
       if (nevents != 0) fprintf(vvp_out, "    %%evctl/c;\n");
 
 }
diff --git a/vvp/compile.h b/vvp/compile.h
index cccc2391a..e98f37ed5 100644
--- a/vvp/compile.h
+++ b/vvp/compile.h
@@ -47,6 +47,7 @@ extern void compile_init(void);
 extern void compile_cleanup(void);
 
 extern bool verbose_flag;
+extern bool warn_array_write_oob;
 
 /*
  * If this file opened, then write debug information to this
diff --git a/vvp/lexor.lex b/vvp/lexor.lex
index 1a6ce88ef..cb45fdd88 100644
--- a/vvp/lexor.lex
+++ b/vvp/lexor.lex
@@ -77,6 +77,7 @@ inline uint64_t strtouint64(const char*str, char**endptr, int base)
   /* These are some special header/footer keywords. */
 ^":ivl_version" { return K_ivl_version; }
 ^":ivl_delay_selection" { return K_ivl_delay_selection; }
+^":ivl_warnings" { return K_ivl_warnings; }
 ^":vpi_module" { return K_vpi_module; }
 ^":vpi_time_precision" { return K_vpi_time_precision; }
 ^":file_names" { return K_file_names; }
diff --git a/vvp/lib_main.cc b/vvp/lib_main.cc
index 3e1832b6e..398eaf1c7 100644
--- a/vvp/lib_main.cc
+++ b/vvp/lib_main.cc
@@ -53,6 +53,7 @@ extern "C" const char*optarg;
 #endif
 
 bool verbose_flag = false;
+bool warn_array_write_oob = false;
 static int vvp_return_value = 0;
 static int vvp_used = 0;
 
@@ -214,6 +215,12 @@ void set_delay_selection(const char* sel)
       delete[] sel;
 }
 
+void set_warning_flags(const char* sel)
+{
+      warn_array_write_oob = strchr(sel, 's') != 0;
+      delete[] sel;
+}
+
 static void final_cleanup()
 {
       vvp_object::cleanup();
diff --git a/vvp/parse.y b/vvp/parse.y
index bd8dba1bf..ed2a94335 100644
--- a/vvp/parse.y
+++ b/vvp/parse.y
@@ -105,7 +105,7 @@ static struct __vpiModPath*modpath_dst = 0;
 %token K_VAR_S K_VAR_STR K_VAR_I K_VAR_R K_VAR_2S K_VAR_2U
 %token K_vpi_call K_vpi_call_w K_vpi_call_i
 %token K_vpi_func K_vpi_func_r K_vpi_func_s
-%token K_ivl_version K_ivl_delay_selection
+%token K_ivl_version K_ivl_delay_selection K_ivl_warnings
 %token K_vpi_module K_vpi_time_precision K_file_names K_file_line
 %token K_PORT_INPUT K_PORT_OUTPUT K_PORT_INOUT K_PORT_MIXED K_PORT_NODIR
 
@@ -153,6 +153,8 @@ header_line
 		{ verify_version($2, $3); }
 	| K_ivl_delay_selection T_STRING ';'
 		{ set_delay_selection($2); }
+	| K_ivl_warnings T_STRING ';'
+		{ set_warning_flags($2); }
 	| K_vpi_module T_STRING ';'
 		{ compile_load_vpi_module($2); }
 	| K_vpi_time_precision '+' T_NUMBER ';'
diff --git a/vvp/parse_misc.h b/vvp/parse_misc.h
index a63cfd11f..c36aafdcc 100644
--- a/vvp/parse_misc.h
+++ b/vvp/parse_misc.h
@@ -38,6 +38,11 @@ extern void verify_version(char *ivl_ver, char* commit);
  */
 extern void set_delay_selection(const char* sel);
 
+/*
+ * Set runtime warning classes embedded in the VVP input file.
+ */
+extern void set_warning_flags(const char* sel);
+
 /*
  * various functions shared by the lexor and the parser.
  */
diff --git a/vvp/vthread.cc b/vvp/vthread.cc
index 98cd41a99..dd5a7db4b 100644
--- a/vvp/vthread.cc
+++ b/vvp/vthread.cc
@@ -20,6 +20,7 @@
 # include  "config.h"
 # include  "vthread.h"
 # include  "codes.h"
+# include  "compile.h"
 # include  "schedule.h"
 # include  "ufunc.h"
 # include  "event.h"
@@ -1076,6 +1077,42 @@ bool of_ADD_WR(vthread_t thr, vvp_code_t)
       return true;
 }
 
+static set<vvp_code_t> warned_array_write_oob;
+
+static void maybe_warn_array_write_oob(vthread_t thr, vvp_code_t cp,
+				       int64_t adr)
+{
+      if (!warn_array_write_oob)
+	    return;
+
+      assert(cp->array);
+
+      bool index_undef = thr->flags[4] == BIT4_1;
+      if (!index_undef && adr >= 0 && (uint64_t) adr < cp->array->get_size())
+	    return;
+
+      if (!warned_array_write_oob.insert(cp).second)
+	    return;
+
+      int left = cp->array->swap_addr ? cp->array->last_addr.get_value()
+				      : cp->array->first_addr.get_value();
+      int right = cp->array->swap_addr ? cp->array->first_addr.get_value()
+				       : cp->array->last_addr.get_value();
+
+      cerr << thr->get_fileline();
+      if (index_undef) {
+	    cerr << "Warning: undefined unpacked array write index for '";
+      } else {
+	    int64_t source_index = adr
+		  + (int64_t) cp->array->first_addr.get_value();
+	    cerr << "Warning: out-of-bounds unpacked array write index "
+		 << source_index << " for '";
+      }
+
+      cerr << cp->array->name << "[" << left << ":" << right
+	   << "]'; write ignored." << endl;
+}
+
 /* %assign/ar <array>, <delay>
  * Generate an assignment event to a real array. Index register 3
  * contains the canonical address of the word in the memory. <delay>
@@ -1088,6 +1125,11 @@ bool of_ASSIGN_AR(vthread_t thr, vvp_code_t cp)
       unsigned delay = cp->bit_idx[0];
       double value = thr->pop_real();
 
+      maybe_warn_array_write_oob(thr, cp, adr);
+
+      if (thr->flags[4] == BIT4_1)
+	    return true;
+
       if (adr >= 0) {
 	    schedule_assign_array_word(cp->array, adr, value, delay);
       }
@@ -1105,6 +1147,11 @@ bool of_ASSIGN_ARD(vthread_t thr, vvp_code_t cp)
       long adr = thr->words[3].w_int;
       double value = thr->pop_real();
 
+      maybe_warn_array_write_oob(thr, cp, adr);
+
+      if (thr->flags[4] == BIT4_1)
+	    return true;
+
       if (adr >= 0) {
 	    vvp_time64_t delay = thr->words[cp->bit_idx[0]].w_uint;
 	    schedule_assign_array_word(cp->array, adr, value, delay);
@@ -1125,6 +1172,11 @@ bool of_ASSIGN_ARE(vthread_t thr, vvp_code_t cp)
       long adr = thr->words[3].w_int;
       double value = thr->pop_real();
 
+      maybe_warn_array_write_oob(thr, cp, adr);
+
+      if (thr->flags[4] == BIT4_1)
+	    return true;
+
       if (adr >= 0) {
 	    if (thr->ecount == 0) {
 		  schedule_assign_array_word(cp->array, adr, value, 0);
@@ -1210,6 +1262,8 @@ bool of_ASSIGN_VEC4_A_D(vthread_t thr, vvp_code_t cp)
 
       vvp_vector4_t val = thr->pop_vec4();
 
+      maybe_warn_array_write_oob(thr, cp, adr);
+
 	// Abort if flags[4] is set. This can happen if the calculation
 	// into an index register failed.
       if (thr->flags[4] == BIT4_1)
@@ -1236,6 +1290,8 @@ bool of_ASSIGN_VEC4_A_E(vthread_t thr, vvp_code_t cp)
 
       vvp_vector4_t val = thr->pop_vec4();
 
+      maybe_warn_array_write_oob(thr, cp, adr);
+
 	// Abort if flags[4] is set. This can happen if the calculation
 	// into an index register failed.
       if (thr->flags[4] == BIT4_1)
@@ -5770,6 +5826,11 @@ bool of_STORE_OBJA(vthread_t thr, vvp_code_t cp)
       vvp_object_t val;
       thr->pop_object(val);
 
+      maybe_warn_array_write_oob(thr, cp, adr);
+
+      if (thr->flags[4] == BIT4_1)
+	    return true;
+
       cp->array->set_word(adr, val);
 
       return true;
@@ -6089,8 +6150,10 @@ static bool storea(vthread_t thr, vvp_code_t cp)
       ELEM val;
       pop_value(thr, val, 0);
 
+      unsigned adr = thr->words[idx].w_int;
+      maybe_warn_array_write_oob(thr, cp, adr);
+
       if (thr->flags[4] != BIT4_1) {
-	    unsigned adr = thr->words[idx].w_int;
 	    cp->array->set_word(adr, val);
       }
 
@@ -6191,6 +6254,8 @@ bool of_STORE_VEC4A(vthread_t thr, vvp_code_t cp)
       long adr = adr_index? thr->words[adr_index].w_int : 0;
       int64_t off = off_index ? thr->words[off_index].w_int : 0;
 
+      maybe_warn_array_write_oob(thr, cp, adr);
+
 	// Suppress action if flags-4 is true.
       if (thr->flags[4] == BIT4_1) {
 	    thr->pop_vec4(1);