diff --git a/include/verilated.cpp b/include/verilated.cpp
index b32c99ad9..53f1b3999 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -143,6 +143,15 @@ WDataOutP VL_ZERO_RESET_W(int obits, WDataOutP outwp) {
     return outwp;
 }
 
+//===========================================================================
+// Debug
+
+void _VL_DEBUG_PRINT_W(int lbits, WDataInP iwp) {
+    VL_PRINTF("  Data: w%d: ", lbits);
+    for (int i=VL_WORDS_I(lbits)-1; i>=0; i--) { VL_PRINTF("%08x ",iwp[i]); }
+    VL_PRINTF("\n");
+}
+
 //===========================================================================
 // Slow math
 
diff --git a/include/verilated.h b/include/verilated.h
index 1a8e20896..6ebb3e83b 100644
--- a/include/verilated.h
+++ b/include/verilated.h
@@ -328,11 +328,7 @@ static inline IData  VL_EXTENDSIGN_I(int lbits, IData lhs) { return (-((lhs)&(VL
 static inline QData  VL_EXTENDSIGN_Q(int lbits, QData lhs) { return (-((lhs)&(VL_ULL(1)<<(lbits-1)))); }
 
 // Debugging prints
-static inline void _VL_DEBUG_PRINT_W(int lbits, WDataInP iwp) {
-    printf("  Data: w%d: ", lbits);
-    for (int i=VL_WORDS_I(lbits)-1; i>=0; i--) { printf("%08x ",iwp[i]); }
-    printf("\n");
-}
+void _VL_DEBUG_PRINT_W(int lbits, WDataInP iwp);
 
 //=========================================================================
 // Pli macros
diff --git a/src/V3Error.h b/src/V3Error.h
index b7f83943e..d39367724 100644
--- a/src/V3Error.h
+++ b/src/V3Error.h
@@ -203,7 +203,7 @@ inline void v3errorEnd(ostringstream& sstr) { V3Error::v3errorEnd(sstr); }
 // For use in V3Ast static functions only
 #define UASSERT_STATIC(condition,stmsg) { if (!(condition)) { cerr<<"Internal Error: "<<__FILE__<<":"<<dec<<__LINE__<<":"<<(stmsg)<<endl; abort(); } }
 
-#define V3ERROR_NA v3error("Internal: Unexpected Call")
+#define V3ERROR_NA { v3error("Internal: Unexpected Call"); v3fatalSrc("Unexpected Call"); }
 
 //----------------------------------------------------------------------
 
diff --git a/test_regress/driver.pl b/test_regress/driver.pl
index c497c2a70..73ff5b9fd 100755
--- a/test_regress/driver.pl
+++ b/test_regress/driver.pl
@@ -44,6 +44,7 @@ my $opt_benchmark;
 my @opt_tests;
 my $opt_gdb;
 my $opt_gdbbt;
+my $opt_gdbsim;
 my $opt_iv;
 my $opt_jobs = 1;
 my $opt_nc;
@@ -62,6 +63,7 @@ if (! GetOptions (
 		  "debug"	=> \&debug,
 		  "gdb!"	=> \$opt_gdb,
 		  "gdbbt!"	=> \$opt_gdbbt,
+		  "gdbsim!"	=> \$opt_gdbsim,
 		  "help"	=> \&usage,
 		  "iverilog!"	=> \$opt_iv,
 		  "j=i"		=> \$opt_jobs,
@@ -531,7 +533,8 @@ sub execute {
 	#&& (!$param{needs_v4} || -r "$ENV{VERILATOR_ROOT}/src/V3Gate.cpp")
 	) {
 	$self->_run(logfile=>"$self->{obj_dir}/vlt_sim.log",
-		    cmd=>["$self->{obj_dir}/$param{VM_PREFIX}",
+		    cmd=>[(($opt_gdbsim ? "gdbrun ":"")
+			   ."$self->{obj_dir}/$param{VM_PREFIX}"),
 			  @{$param{all_run_flags}},
 			  ],
 		    %param,
@@ -1143,13 +1146,17 @@ specifies the number of simulation cycles (for tests that support it).
 
 =item --gdb
 
-Run verilator under the debugger.
+Run Verilator under the debugger.
 
 =item --gdbbt
 
-Run verilator under the debugger, only to print backtrace information.
+Run Verilator under the debugger, only to print backtrace information.
 Requires --debug.
 
+=item --gdbsim
+
+Run Verilator generated executable under the debugger.
+
 =item --help
 
 Displays this message and program version and exits.