diff --git a/hw/xwin/winprefslex.l b/hw/xwin/winprefslex.l
index ba8aea696..15f707766 100644
--- a/hw/xwin/winprefslex.l
+++ b/hw/xwin/winprefslex.l
@@ -37,14 +37,10 @@
 #include <string.h>
 #include "winprefsyacc.h"
 
-extern YYSTYPE yylval;
-extern char *yytext;
 extern int yyparse(void);
 
 extern void ErrorF (const char* /*f*/, ...);
 
-int yylineno;
-
 /* Copy the parsed string, must be free()d in yacc parser */
 static char *makestr(char *str)
 {
@@ -62,6 +58,9 @@ static char *makestr(char *str)
 %}
 
 %option yylineno
+%option nounput
+%option noinput
+%option never-interactive
 
 %%
 \#.*[\r\n]              { /* comment */ return NEWLINE; }
diff --git a/hw/xwin/winprefsyacc.y b/hw/xwin/winprefsyacc.y
index 0acf160e4..19c2f4067 100644
--- a/hw/xwin/winprefsyacc.y
+++ b/hw/xwin/winprefsyacc.y
@@ -37,6 +37,7 @@
 #endif
 #include <stdio.h>
 #include <stdlib.h>
+#define _STDLIB_H 1 /* bison checks this to know if stdlib has been included */
 #include <string.h>
 #include "winprefs.h"
 
@@ -80,7 +81,6 @@ static void CloseSysMenu(void);
 
 static int yyerror (char *s);
 
-extern void ErrorF (const char* /*f*/, ...);
 extern char *yytext;
 extern int yylex(void);