diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 3aba792..c894ec5 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1191,6 +1191,8 @@
 			if (po == NULL)
 				return NULL;
 			prompt = PyString_AsString(po);
+			if (prompt == NULL)
+				return NULL;
 		}
 		else {
 			po = NULL;