diff --git a/ext/random/engine_mt19937.c b/ext/random/engine_mt19937.c
index 7c9d1741d81..64009990910 100644
--- a/ext/random/engine_mt19937.c
+++ b/ext/random/engine_mt19937.c
@@ -330,11 +330,11 @@ PHP_METHOD(Random_Engine_Mt19937, __serialize)
 
 	/* state */
 	array_init(&t);
+	zend_hash_next_index_insert(Z_ARRVAL_P(return_value), &t);
 	if (!engine->engine.algo->serialize(engine->engine.state, Z_ARRVAL(t))) {
 		zend_throw_exception(NULL, "Engine serialize failed", 0);
 		RETURN_THROWS();
 	}
-	zend_hash_next_index_insert(Z_ARRVAL_P(return_value), &t);
 }
 /* }}} */