diff --git a/Python/_warnings.c b/Python/_warnings.c
index 07fd683e53e..99f6071a0c7 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -517,6 +517,7 @@ setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
     }
     else {
         const char *module_str = _PyUnicode_AsString(*module);
+        Py_XDECREF(*filename);
         if (module_str == NULL)
                 goto handle_error;
         if (strcmp(module_str, "__main__") == 0) {