diff --git a/Zend/zend_builtin_functions.c b/Zend/zend_builtin_functions.c
index b23ee3a5333..ce4b68ae1fe 100644
--- a/Zend/zend_builtin_functions.c
+++ b/Zend/zend_builtin_functions.c
@@ -1808,7 +1808,7 @@ ZEND_FUNCTION(zend_test_func)
 #ifdef ZTS
 ZEND_FUNCTION(zend_thread_id)
 {
-	RETURN_LONG(tsrm_thread_id());
+	RETURN_LONG((long)tsrm_thread_id());
 }
 #endif
 #endif