1 files changed, 3 insertions, 0 deletions
diff --git a/Python/errors.c b/Python/errors.c
index 9658afeb9f..1783084c33 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -218,6 +218,9 @@ PyErr_SetString(PyObject *exception, const char *string)
 PyObject* _Py_HOT_FUNCTION
 PyErr_Occurred(void)
 {
+    /* The caller must hold the GIL. */
+    assert(PyGILState_Check());
+
     PyThreadState *tstate = _PyThreadState_GET();
     return _PyErr_Occurred(tstate);
 }