diff --git a/src/proto/if_lua.pro b/src/proto/if_lua.pro
index fb80ae0..3bac4cc 100644
--- a/src/proto/if_lua.pro
+++ b/src/proto/if_lua.pro
@@ -1,4 +1,5 @@
 /* if_lua.c */
+int lua_enabled __ARGS((int verbose));
 void lua_end __ARGS((void));
 void ex_lua __ARGS((exarg_T *eap));
 void ex_luado __ARGS((exarg_T *eap));