1 files changed, 3 insertions, 0 deletions
diff --git a/Python/frame.c b/Python/frame.c
index 52f6ef4..b1525cc 100644
--- a/Python/frame.c
+++ b/Python/frame.c
@@ -127,6 +127,9 @@ _PyFrame_Clear(_PyInterpreterFrame *frame)
      * to have cleared the enclosing generator, if any. */
     assert(frame->owner != FRAME_OWNED_BY_GENERATOR ||
         _PyFrame_GetGenerator(frame)->gi_frame_state == FRAME_CLEARED);
+    // GH-99729: Clearing this frame can expose the stack (via finalizers). It's
+    // crucial that this frame has been unlinked, and is no longer visible:
+    assert(_PyThreadState_GET()->cframe->current_frame != frame);
     if (frame->frame_obj) {
         PyFrameObject *f = frame->frame_obj;
         frame->frame_obj = NULL;