diff --git a/src/dispextern.h b/src/dispextern.h
index 2b53fa8d8fd..18b05b5db0e 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -2739,7 +2739,7 @@ int ascii_face_of_lisp_face P_ ((struct frame *, int));
 void prepare_face_for_display P_ ((struct frame *, struct face *));
 int xstricmp P_ ((const unsigned char *, const unsigned char *));
 int lookup_face P_ ((struct frame *, Lisp_Object *, int, struct face *));
-int lookup_named_face P_ ((struct frame *, Lisp_Object, int));
+int lookup_named_face P_ ((struct frame *, Lisp_Object, int, int));
 int smaller_face P_ ((struct frame *, int, int));
 int face_with_height P_ ((struct frame *, int, int));
 int lookup_derived_face P_ ((struct frame *, Lisp_Object, int, int));