diff --git a/data/glr.c b/data/glr.c
index 3c69ac82..a1331084 100644
--- a/data/glr.c
+++ b/data/glr.c
@@ -198,6 +198,12 @@ static YYLTYPE yyloc_default;
 #  define yyfalse 0
 #endif
 
+#if defined (__STDC__) || defined (__cplusplus)
+   typedef signed char yysigned_char;
+#else
+   typedef short yysigned_char;
+#endif
+
 /*-----------------.
 | GCC extensions.  |
 `-----------------*/
diff --git a/data/yacc.c b/data/yacc.c
index cb690bb7..cf90c827 100644
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -307,6 +307,12 @@ b4_location_if(
 
 #endif
 
+#if defined (__STDC__) || defined (__cplusplus)
+   typedef signed char yysigned_char;
+#else
+   typedef short yysigned_char;
+#endif
+
 /* YYFINAL -- State number of the termination state. */
 #define YYFINAL  b4_final_state_number
 #define YYLAST   b4_last