diff --git a/Makefile.in b/Makefile.in
index fa1796705..7ff804088 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -239,7 +239,7 @@ lexor.cc: $(srcdir)/lexor.lex
 lexor_keyword.o: lexor_keyword.cc parse.h
 
 lexor_keyword.cc: $(srcdir)/lexor_keyword.gperf
-	gperf -o -i 7 -C -k 1-4,$$ -L ANSI-C -H keyword_hash -N check_identifier -t $(srcdir)/lexor_keyword.gperf > lexor_keyword.cc || (rm -f lexor_keyword.cc ; false)
+	gperf -o -i 7 -C -k 1-4,$$ -H keyword_hash -N check_identifier -t $(srcdir)/lexor_keyword.gperf > lexor_keyword.cc || (rm -f lexor_keyword.cc ; false)
 
 iverilog-vpi.man: $(srcdir)/iverilog-vpi.man.in version.exe
 	./version.exe `head -1 $(srcdir)/iverilog-vpi.man.in`'\n' > $@
diff --git a/autoconf.sh b/autoconf.sh
index 2b5c3f319..b22527391 100644
--- a/autoconf.sh
+++ b/autoconf.sh
@@ -10,4 +10,4 @@ echo "Autoconf in root..."
 autoconf -f
 
 echo "Precompiling lexor_keyword.gperf"
-gperf -o -i 7 -C -k 1-4,\$ -L ANSI-C -H keyword_hash -N check_identifier -t ./lexor_keyword.gperf > lexor_keyword.cc
+gperf -o -i 7 -C -k 1-4,\$ -H keyword_hash -N check_identifier -t ./lexor_keyword.gperf > lexor_keyword.cc
diff --git a/lexor_keyword.gperf b/lexor_keyword.gperf
index 83681aba3..a37513c4b 100644
--- a/lexor_keyword.gperf
+++ b/lexor_keyword.gperf
@@ -1,5 +1,8 @@
+%language=C++
+%define class-name Lkwd
+
 %{
-/* Command-line: gperf -o -i 1 -C -k 1-3,$ -L C -H keyword_hash -N check_identifier -tT lexor_keyword.gperf */
+/* Command-line: gperf -o -i 7 -C -k 1-4,$ -H keyword_hash -N check_identifier -t lexor_keyword.gperf */
 
 #include "config.h"
 #include "parse_misc.h"
@@ -194,7 +197,7 @@ int lexor_keyword_mask = 0;
 
 int lexor_keyword_code(const char*str, unsigned nstr)
 {
-      const struct lexor_keyword*rc = check_identifier(str, nstr);
+      const struct lexor_keyword*rc = Lkwd::check_identifier(str, nstr);
       if (rc == 0)
 	  return IDENTIFIER;
       else if ((rc->mask & lexor_keyword_mask) == 0)