diff --git a/lib/lua/src/loadlib.c b/lib/lua/src/loadlib.c
index 0d401eba1..702e8749a 100644
--- a/lib/lua/src/loadlib.c
+++ b/lib/lua/src/loadlib.c
@@ -73,7 +73,7 @@ static void *ll_load (lua_State *L, const char *path) {
 
 
 static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
-  lua_CFunction f = (lua_CFunction)dlsym(lib, sym);
+  lua_CFunction f = __extension__(lua_CFunction)dlsym(lib, sym);
   if (f == NULL) lua_pushstring(L, dlerror());
   return f;
 }