diff --git a/src/auxiliar.c b/src/auxiliar.c
index 18fa8e4..5251549 100644
--- a/src/auxiliar.c
+++ b/src/auxiliar.c
@@ -143,7 +143,7 @@ void *auxiliar_getgroupudata(lua_State *L, const char *groupname, int objidx) {
 * otherwise
 \*-------------------------------------------------------------------------*/
 void *auxiliar_getclassudata(lua_State *L, const char *classname, int objidx) {
-    return luaL_checkudata(L, objidx, classname);
+    return luaL_testudata(L, objidx, classname);
 }
 
 /*-------------------------------------------------------------------------*\