diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 0309f1de..718b603 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1840,7 +1840,7 @@
 			}
 			break;
 		}
-		temp = PyNumber_Add(result, item);
+		temp = PyNumber_InPlaceAdd(result, item);
 		Py_DECREF(result);
 		Py_DECREF(item);
 		result = temp;