diff --git a/usr.sbin/kbdcontrol/lex.h b/usr.sbin/kbdcontrol/lex.h
index 91e1e54d1a2a..17e10c266f0e 100644
--- a/usr.sbin/kbdcontrol/lex.h
+++ b/usr.sbin/kbdcontrol/lex.h
@@ -69,4 +69,4 @@ extern int number;
 extern char letter;
 extern FILE *yyin;
 
-extern int yylex __P((void));
+extern int yylex(void);