diff --git a/src/V3EmitC.cpp b/src/V3EmitC.cpp
index 8406bf6f7..f50b8077f 100644
--- a/src/V3EmitC.cpp
+++ b/src/V3EmitC.cpp
@@ -719,7 +719,7 @@ class EmitCImp : EmitCStmts {
 			varname = ": "+nodep->lhsp()->castVarRef()->varp()->prettyName();
 		    }
 		    puts(")) cout<<\"\tCHANGE: "+nodep->fileline()->ascii()
-			 +varname+"\"<<endl; );");
+			 +varname+"\"<<endl; );\n");
 		}
 	    }
 	}
diff --git a/test_regress/driver.pl b/test_regress/driver.pl
index fc67ae301..d03e0b13a 100755
--- a/test_regress/driver.pl
+++ b/test_regress/driver.pl
@@ -326,7 +326,7 @@ sub compile {
 
     if ($param{vcs}) {
 	$self->_make_top();
-	$self->_run(logfile=>"obj_dir/".$self->{name}."_vcs_compile.log",
+	$self->_run(logfile=>"obj_dir/".$self->{name}."__vcs_compile.log",
 		    fails=>$param{fails},
 		    cmd=>[($ENV{VERILATOR_VCS}||"vcs"),
 			  @{$param{vcs_flags}},
@@ -340,7 +340,7 @@ sub compile {
     }
     if ($param{nc}) {
 	$self->_make_top();
-	$self->_run(logfile=>"obj_dir/".$self->{name}."_nc_compile.log",
+	$self->_run(logfile=>"obj_dir/".$self->{name}."__nc_compile.log",
 		    fails=>$param{fails},
 		    cmd=>[($ENV{VERILATOR_NCVERILOG}||"ncverilog"),
 			  @{$param{nc_flags}},
@@ -388,7 +388,7 @@ sub compile {
 	    return 1;
 	}
 
-	$self->_run(logfile=>"obj_dir/".$self->{name}."_simx_compile.log",
+	$self->_run(logfile=>"obj_dir/".$self->{name}."__simx_compile.log",
 		    fails=>$param{fails},
 		    expect=>$param{expect},
 		    cmd=>\@v3args);
@@ -402,7 +402,7 @@ sub compile {
 		$self->_sp_preproc(%param);
 	    }
 	    $self->oprint("GCC\n");
-	    $self->_run(logfile=>"obj_dir/".$self->{name}."_simx_gcc.log",
+	    $self->_run(logfile=>"obj_dir/".$self->{name}."__simx_gcc.log",
 			cmd=>["cd obj_dir && ",
 			      "make", "-f".getcwd()."/Makefile_obj",
 			      "VM_PREFIX=$self->{VM_PREFIX}",
@@ -423,7 +423,7 @@ sub execute {
     if ($param{vcs}) {
 	#my $fh = IO::File->new(">simv.key") or die "%Error: $! simv.key,";
 	#$fh->print("quit\n"); $fh->close;
-	$self->_run(logfile=>"obj_dir/".$self->{name}."_simv.log",
+	$self->_run(logfile=>"obj_dir/".$self->{name}."__simv.log",
 		    cmd=>["./simv",],
 		    %param,
 		    expect=>undef,	# vcs expect isn't the same
@@ -432,7 +432,7 @@ sub execute {
     if ($param{v3}
 	#&& (!$param{needs_v4} || -r "$ENV{VERILATOR_ROOT}/src/V3Gate.cpp")
 	) {
-	$self->_run(logfile=>"obj_dir/".$self->{name}."_simx.log",
+	$self->_run(logfile=>"obj_dir/".$self->{name}."__simx.log",
 		    cmd=>["obj_dir/$param{VM_PREFIX}",
 			  ],
 		    %param,
@@ -633,7 +633,7 @@ sub _make_main {
 	    $fh->print("    SpTraceVcdCFile* tfp = new SpTraceVcdCFile;\n");
 	}
 	$fh->print("    topp->trace (tfp, 99);\n");
-	$fh->print("    tfp->open (\"obj_dir/".$self->{name}."_simx.vcd\");\n");
+	$fh->print("    tfp->open (\"obj_dir/".$self->{name}."__simx.vcd\");\n");
 	$fh->print("#endif\n");
     }
 
diff --git a/test_regress/t/t_assert_cover.pl b/test_regress/t/t_assert_cover.pl
index 085adda20..f92de1038 100755
--- a/test_regress/t/t_assert_cover.pl
+++ b/test_regress/t/t_assert_cover.pl
@@ -33,9 +33,9 @@ if ($Last_Self->{nc}) {
 			    "-test ${name} ${cf}"]);
 }
 
-file_grep ("obj_dir/$Last_Self->{name}_simx.log", qr/COVER: Cyc==4/);
-file_grep ("obj_dir/$Last_Self->{name}_simx.log", qr/COVER: Cyc==5/);
-file_grep ("obj_dir/$Last_Self->{name}_simx.log", qr/COVER: Cyc==6/);
+file_grep ("obj_dir/$Last_Self->{name}__simx.log", qr/COVER: Cyc==4/);
+file_grep ("obj_dir/$Last_Self->{name}__simx.log", qr/COVER: Cyc==5/);
+file_grep ("obj_dir/$Last_Self->{name}__simx.log", qr/COVER: Cyc==6/);
 
 # Allow old Perl format dump, or new binary dump
 file_grep ($Last_Self->{coverage_filename}, qr/(cyc_eq_5.*,c=>[^0]|cyc_eq_5.* [1-9][0-9]*\n)/);
diff --git a/test_regress/t/t_trace_ena_cc.pl b/test_regress/t/t_trace_ena_cc.pl
index 823bc29a2..b97e58951 100644
--- a/test_regress/t/t_trace_ena_cc.pl
+++ b/test_regress/t/t_trace_ena_cc.pl
@@ -19,7 +19,7 @@ execute (
 if ($Last_Self->{v3}) {
     file_grep     ("obj_dir/V$Last_Self->{name}__Trace__Slow.cpp", qr/c_trace_on\"/x);
     file_grep_not ("obj_dir/V$Last_Self->{name}__Trace__Slow.cpp", qr/_trace_off\"/x);
-    file_grep     ("obj_dir/$Last_Self->{name}_simx.vcd", qr/\$enddefinitions/x);
+    file_grep     ("obj_dir/$Last_Self->{name}__simx.vcd", qr/\$enddefinitions/x);
 }
 
 ok(1);
diff --git a/test_regress/t/t_trace_ena_sc.pl b/test_regress/t/t_trace_ena_sc.pl
index 89acfb961..067a7da60 100755
--- a/test_regress/t/t_trace_ena_sc.pl
+++ b/test_regress/t/t_trace_ena_sc.pl
@@ -18,7 +18,7 @@ execute (
 
 if ($Last_Self->{v3}) {
     # Note more checks in _cc.pl
-    file_grep     ("obj_dir/$Last_Self->{name}_simx.vcd", qr/\$enddefinitions/x);
+    file_grep     ("obj_dir/$Last_Self->{name}__simx.vcd", qr/\$enddefinitions/x);
 }
 
 ok(1);
diff --git a/test_regress/t/t_trace_ena_sp.pl b/test_regress/t/t_trace_ena_sp.pl
index c4a10bd9d..8a27293da 100755
--- a/test_regress/t/t_trace_ena_sp.pl
+++ b/test_regress/t/t_trace_ena_sp.pl
@@ -18,7 +18,7 @@ execute (
 
 if ($Last_Self->{v3}) {
     # Note more checks in _cc.pl
-    file_grep     ("obj_dir/$Last_Self->{name}_simx.vcd", qr/\$enddefinitions/x);
+    file_grep     ("obj_dir/$Last_Self->{name}__simx.vcd", qr/\$enddefinitions/x);
 }
 
 ok(1);
diff --git a/test_regress/t/t_trace_off_cc.pl b/test_regress/t/t_trace_off_cc.pl
index 2fec873c4..32377debc 100755
--- a/test_regress/t/t_trace_off_cc.pl
+++ b/test_regress/t/t_trace_off_cc.pl
@@ -17,7 +17,7 @@ execute (
 	 );
 
 if ($Last_Self->{v3}) {
-    !-r "obj_dir/$Last_Self->{name}_simx.vcd" or $Last_Self->error("Tracing should be off\n");
+    !-r "obj_dir/$Last_Self->{name}__simx.vcd" or $Last_Self->error("Tracing should be off\n");
 }
 
 ok(1);
diff --git a/test_regress/t/t_trace_off_sc.pl b/test_regress/t/t_trace_off_sc.pl
index 0c780e017..d564b6777 100755
--- a/test_regress/t/t_trace_off_sc.pl
+++ b/test_regress/t/t_trace_off_sc.pl
@@ -17,7 +17,7 @@ execute (
 	 );
 
 if ($Last_Self->{v3}) {
-    !-r "obj_dir/$Last_Self->{name}_simx.vcd" or $Last_Self->error("Tracing should be off\n");
+    !-r "obj_dir/$Last_Self->{name}__simx.vcd" or $Last_Self->error("Tracing should be off\n");
 }
 
 ok(1);
diff --git a/test_regress/t/t_trace_off_sp.pl b/test_regress/t/t_trace_off_sp.pl
index 5fa8787c2..b678c2c07 100755
--- a/test_regress/t/t_trace_off_sp.pl
+++ b/test_regress/t/t_trace_off_sp.pl
@@ -17,7 +17,7 @@ execute (
 	 );
 
 if ($Last_Self->{v3}) {
-    !-r "obj_dir/$Last_Self->{name}_simx.vcd" or $Last_Self->error("Tracing should be off\n");
+    !-r "obj_dir/$Last_Self->{name}__simx.vcd" or $Last_Self->error("Tracing should be off\n");
 }
 
 ok(1);
diff --git a/test_regress/t/t_trace_public_func.cpp b/test_regress/t/t_trace_public_func.cpp
index ee585cc39..77e372a4a 100644
--- a/test_regress/t/t_trace_public_func.cpp
+++ b/test_regress/t/t_trace_public_func.cpp
@@ -25,7 +25,7 @@ int main(int argc, char **argv, char **env) {
 
     SpTraceVcdCFile* tfp = new SpTraceVcdCFile;
     top->trace(tfp,99);
-    tfp->open("obj_dir/t_trace_public_func_simx.vcd");
+    tfp->open("obj_dir/t_trace_public_func__simx.vcd");
 
     while (main_time <= 20) {
 	top->CLK   = (main_time/dt_2)%2;
diff --git a/test_regress/t/t_trace_public_func.pl b/test_regress/t/t_trace_public_func.pl
index 6f6cd0ff9..fe545537f 100755
--- a/test_regress/t/t_trace_public_func.pl
+++ b/test_regress/t/t_trace_public_func.pl
@@ -19,7 +19,7 @@ if ($Last_Self->{v3}) {
 	     check_finished=>1,
 	     );
 
-    ok(vcd_identical ("obj_dir/$Last_Self->{name}_simx.vcd",
+    ok(vcd_identical ("obj_dir/$Last_Self->{name}__simx.vcd",
 		      "t/$Last_Self->{name}.out"));
 }
 else {
diff --git a/test_regress/t/t_trace_public_sig.cpp b/test_regress/t/t_trace_public_sig.cpp
index 8f9ad547f..e89dbb0ed 100644
--- a/test_regress/t/t_trace_public_sig.cpp
+++ b/test_regress/t/t_trace_public_sig.cpp
@@ -25,7 +25,7 @@ int main(int argc, char **argv, char **env) {
 
     SpTraceVcdCFile* tfp = new SpTraceVcdCFile;
     top->trace(tfp,99);
-    tfp->open("obj_dir/t_trace_public_sig_simx.vcd");
+    tfp->open("obj_dir/t_trace_public_sig__simx.vcd");
 
     while (main_time <= 20) {
 	top->CLK   = (main_time/dt_2)%2;
diff --git a/test_regress/t/t_trace_public_sig.pl b/test_regress/t/t_trace_public_sig.pl
index b628bff74..c2edec50a 100755
--- a/test_regress/t/t_trace_public_sig.pl
+++ b/test_regress/t/t_trace_public_sig.pl
@@ -19,7 +19,7 @@ if ($Last_Self->{v3}) {
 	     check_finished=>1,
 	     );
 
-    ok(vcd_identical ("obj_dir/$Last_Self->{name}_simx.vcd",
+    ok(vcd_identical ("obj_dir/$Last_Self->{name}__simx.vcd",
 		      "t/$Last_Self->{name}.out"));
 }
 else {
diff --git a/test_regress/t/t_var_escape.pl b/test_regress/t/t_var_escape.pl
index 22dd5bca9..7113b662f 100755
--- a/test_regress/t/t_var_escape.pl
+++ b/test_regress/t/t_var_escape.pl
@@ -16,9 +16,9 @@ execute (
 	 );
 
 if ($Last_Self->{v3}) {
-    file_grep     ("obj_dir/$Last_Self->{name}_simx.vcd", qr/\$enddefinitions/x);
+    file_grep     ("obj_dir/$Last_Self->{name}__simx.vcd", qr/\$enddefinitions/x);
     my $sig = quotemeta("bra[ket]slash/dash-colon:9");
-    file_grep     ("obj_dir/$Last_Self->{name}_simx.vcd", qr/$sig/);
+    file_grep     ("obj_dir/$Last_Self->{name}__simx.vcd", qr/$sig/);
 }
 
 ok(1);