diff --git a/Makefile.in b/Makefile.in
index acef67ec7..2304cda5b 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -267,7 +267,7 @@ 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 1-4,6,9,$$ -L ANSI-C -H keyword_hash -N check_identifier -t $(srcdir)/lexor_keyword.gperf > lexor_keyword.cc || (rm -f lexor_keyword.cc ; false)
+	gperf -o -i 7 -C -k 1-4,6,9,$$ -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 0840ac287..8eee0af8e 100644
--- a/autoconf.sh
+++ b/autoconf.sh
@@ -10,7 +10,7 @@ echo "Autoconf in root..."
 autoconf -f
 
 echo "Precompiling lexor_keyword.gperf"
-gperf -o -i 7 -C -k 1-4,6,9,\$ -L ANSI-C -H keyword_hash -N check_identifier -t ./lexor_keyword.gperf > lexor_keyword.cc
+gperf -o -i 7 -C -k 1-4,6,9,\$ -H keyword_hash -N check_identifier -t ./lexor_keyword.gperf > lexor_keyword.cc
 
 echo "Precompiling vhdlpp/lexor_keyword.gperf"
-(cd vhdlpp ; gperf -o -i 7 --ignore-case -C -k 1-4,6,9,\$ -L ANSI-C -H keyword_hash -N check_identifier -t ./lexor_keyword.gperf > lexor_keyword.cc )
+(cd vhdlpp ; gperf -o -i 7 --ignore-case -C -k 1-4,6,9,\$ -H keyword_hash -N check_identifier -t ./lexor_keyword.gperf > lexor_keyword.cc )
diff --git a/lexor_keyword.gperf b/lexor_keyword.gperf
index 34e994e4a..4bb8d0629 100644
--- a/lexor_keyword.gperf
+++ b/lexor_keyword.gperf
@@ -3,9 +3,11 @@
  * tokenType values are not initialized for the empty table entries.
  */
 %define initializer-suffix ,0,0
+%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 '1-4,6,9,$' -H keyword_hash -N check_identifier -t ./lexor_keyword.gperf  */
 
 #include "config.h"
 #include "parse_misc.h"
@@ -362,7 +364,7 @@ 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)
diff --git a/vhdlpp/Makefile.in b/vhdlpp/Makefile.in
index e3622a7c3..ce796c588 100644
--- a/vhdlpp/Makefile.in
+++ b/vhdlpp/Makefile.in
@@ -124,7 +124,7 @@ parse.h: parse.cc
 lexor_keyword.o: lexor_keyword.cc parse.h
 
 lexor_keyword.cc: $(srcdir)/lexor_keyword.gperf
-	gperf -o -i 7 --ignore-case -C -k 1-4,6,9,$$ -L ANSI-C -H keyword_hash -N check_identifier -t $(srcdir)/lexor_keyword.gperf > lexor_keyword.cc || (rm -f lexor_keyword.cc ; false)
+	gperf -o -i 7 --ignore-case -C -k 1-4,6,9,$$ -H keyword_hash -N check_identifier -t $(srcdir)/lexor_keyword.gperf > lexor_keyword.cc || (rm -f lexor_keyword.cc ; false)
 
 install: all installdirs $(libdir)/ivl$(suffix)/vhdlpp@EXEEXT@
 
diff --git a/vhdlpp/lexor_keyword.gperf b/vhdlpp/lexor_keyword.gperf
index 647798f27..42fd1bc0d 100644
--- a/vhdlpp/lexor_keyword.gperf
+++ b/vhdlpp/lexor_keyword.gperf
@@ -3,9 +3,10 @@
  * tokenType values are not initialized for the empty table entries.
  */
 %define initializer-suffix ,0,0
-
+%language=C++
+%define class-name Lkwd
 %{
-/* Command-line: gperf -o -i 1 --ignore-case -C -k 1-3,$ -L C -H keyword_hash -N check_identifier -tT lexor_keyword.gperf */
+/* Command-line: gperf -o -i 7 --ignore-case -C -k '1-4,6,9,$' -H keyword_hash -N check_identifier -t lexor_keyword.gperf  */
 
 #include "vhdlpp_config.h"
 #include <cstring>
@@ -134,7 +135,7 @@ int lexor_keyword_mask = GN_KEYWORD_2008;
 
 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)