diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index 3710dfd3a..f5e141701 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -1467,7 +1467,7 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
                 i += consumed;
             } else {
                 fl->v3fatal("Invalid option: " << argv[i] << parser.getSuggestion(argv[i]));
-                ++i;
+                ++i;  // LCOV_EXCL_LINE
             }
         } else {
             // Filename
@@ -1643,21 +1643,6 @@ string V3Options::parseFileArg(const string& optdir, const string& relfilename)
 
 //======================================================================
 
-//! Utility to see if we have a language extension argument and if so add it.
-bool V3Options::parseLangExt(const char* swp,  //!< argument text
-                             const char* langswp,  //!< option to match
-                             const V3LangCode& lc) {  //!< language code
-    const int len = strlen(langswp);
-    if (!strncmp(swp, langswp, len)) {
-        addLangExt(swp + len, lc);
-        return true;
-    } else {
-        return false;
-    }
-}
-
-//======================================================================
-
 void V3Options::showVersion(bool verbose) {
     cout << version();
     cout << endl;
diff --git a/src/V3Options.h b/src/V3Options.h
index b8b2c7082..3668fe605 100644
--- a/src/V3Options.h
+++ b/src/V3Options.h
@@ -376,7 +376,6 @@ private:
     void coverage(bool flag) { m_coverageLine = m_coverageToggle = m_coverageUser = flag; }
     static bool suffixed(const string& sw, const char* arg);
     static string parseFileArg(const string& optdir, const string& relfilename);
-    bool parseLangExt(const char* swp, const char* langswp, const V3LangCode& lc);
     string filePathCheckOneDir(const string& modname, const string& dirname);
     static int stripOptionsForChildRun(const string& opt, bool forTop);
 
diff --git a/src/VlcMain.cpp b/src/VlcMain.cpp
index f29fef2c4..f8c57d7c8 100644
--- a/src/VlcMain.cpp
+++ b/src/VlcMain.cpp
@@ -83,7 +83,7 @@ void VlcOptions::parseOptsList(int argc, char** argv) {
                 i += consumed;
             } else {
                 v3fatal("Invalid option: " << argv[i] << parser.getSuggestion(argv[i]));
-                ++i;
+                ++i;  // LCOV_EXCL_LINE
             }
         } else {
             addReadFile(argv[i]);
diff --git a/test_regress/t/t_math_msvc_64.v b/test_regress/t/t_flag_compiler.v
similarity index 100%
rename from test_regress/t/t_math_msvc_64.v
rename to test_regress/t/t_flag_compiler.v
diff --git a/test_regress/t/t_flag_compiler_clang.pl b/test_regress/t/t_flag_compiler_clang.pl
new file mode 100755
index 000000000..edd331316
--- /dev/null
+++ b/test_regress/t/t_flag_compiler_clang.pl
@@ -0,0 +1,24 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+top_filename("t/t_flag_compiler.v");
+
+compile(
+    verilator_flags2 => ["--compiler clang"],
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_flag_compiler_gcc.pl b/test_regress/t/t_flag_compiler_gcc.pl
new file mode 100755
index 000000000..faaedc67a
--- /dev/null
+++ b/test_regress/t/t_flag_compiler_gcc.pl
@@ -0,0 +1,24 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+top_filename("t/t_flag_compiler.v");
+
+compile(
+    verilator_flags2 => ["--compiler gcc"],
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_math_msvc_64.pl b/test_regress/t/t_flag_compiler_msvc.pl
similarity index 94%
rename from test_regress/t/t_math_msvc_64.pl
rename to test_regress/t/t_flag_compiler_msvc.pl
index 2769c27e2..01c70152c 100755
--- a/test_regress/t/t_math_msvc_64.pl
+++ b/test_regress/t/t_flag_compiler_msvc.pl
@@ -10,6 +10,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 scenarios(simulator => 1);
 
+top_filename("t/t_flag_compiler.v");
+
 compile(
     verilator_flags2 => ["--compiler msvc"],  # Bug requires msvc
     );
diff --git a/test_regress/t/t_flag_j_bad.out b/test_regress/t/t_flag_j_bad.out
new file mode 100644
index 000000000..2fe652c5d
--- /dev/null
+++ b/test_regress/t/t_flag_j_bad.out
@@ -0,0 +1,2 @@
+%Error: -j accepts positive integer, but '0' is passed
+%Error: Exiting due to
diff --git a/test_regress/t/t_flag_j_bad.pl b/test_regress/t/t_flag_j_bad.pl
new file mode 100755
index 000000000..ee3d0fdc8
--- /dev/null
+++ b/test_regress/t/t_flag_j_bad.pl
@@ -0,0 +1,22 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(vlt => 1);
+
+top_filename("t/t_flag_werror.v");
+
+lint(
+    fails => 1,
+    verilator_flags => [qw(-j 0 --build)],
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_flag_make_bad.out b/test_regress/t/t_flag_make_bad.out
new file mode 100644
index 000000000..d3a472dd3
--- /dev/null
+++ b/test_regress/t/t_flag_make_bad.out
@@ -0,0 +1 @@
+%Error: Unknown --make system specified: 'bad_one'
diff --git a/test_regress/t/t_flag_make_bad.pl b/test_regress/t/t_flag_make_bad.pl
new file mode 100755
index 000000000..1c6f23aec
--- /dev/null
+++ b/test_regress/t/t_flag_make_bad.pl
@@ -0,0 +1,20 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(vlt => 1);
+
+lint(
+    verilator_flags2 => ["--make bad_one"],
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_flag_make_gmake.pl b/test_regress/t/t_flag_make_gmake.pl
new file mode 100755
index 000000000..e5caca9d8
--- /dev/null
+++ b/test_regress/t/t_flag_make_gmake.pl
@@ -0,0 +1,21 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2008 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+
+scenarios(simulator => 1);
+
+top_filename("t/t_flag_make_cmake.v");
+
+compile(
+    verilator_flags2 => ['--make gmake'],
+    );
+
+ok(1);
+1;