diff --git a/engine/memobj.c b/engine/memobj.c
index 4030fd7..b83139a 100644
--- a/engine/memobj.c
+++ b/engine/memobj.c
@@ -703,6 +703,8 @@ PH7_PRIVATE sxi32 PH7_MemObjIsNull(ph7_value *pObj) {
 		return !pObj->x.iVal;
 	} else if(pObj->nType & (MEMOBJ_OBJ | MEMOBJ_RES)) {
 		return pObj->x.pOther == 0 ? TRUE : FALSE;
+	} else if(pObj->nType & MEMOBJ_CALL) {
+		return SyBlobLength(&pObj->sBlob) == 0 ? TRUE : FALSE;
 	} else if(pObj->nType & MEMOBJ_STRING) {
 		if(SyBlobLength(&pObj->sBlob) <= 0) {
 			return TRUE;