moduleName can be NULL
diff --git a/Python/errors.c b/Python/errors.c
index 275a065..8327f53 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -604,7 +604,7 @@
 				PyFile_WriteString(": ", f);
 				PyFile_WriteObject(v, f, 0);
 			}
-			Py_DECREF(moduleName);
+			Py_XDECREF(moduleName);
 		}
 		PyFile_WriteString(" in ", f);
 		PyFile_WriteObject(obj, f, 0);