diff --git a/lib/roken/roken.h.in b/lib/roken/roken.h.in
index d4796d902..caf1c852c 100644
--- a/lib/roken/roken.h.in
+++ b/lib/roken/roken.h.in
@@ -676,7 +676,7 @@ unvis(char *cp, int c, int *astate, int flag);
 
 #if !defined(HAVE_VIS) || defined(NEED_VIS_PROTO)
 char *
-vis(char *dst, int c, int flag, int nextc)
+vis(char *dst, int c, int flag, int nextc);
 #endif
 
 ROKEN_CPP_END