diff -up PyQt4_gpl_x11-4.12.3/qpy/QtCore/qpycore_classinfo.cpp.me PyQt4_gpl_x11-4.12.3/qpy/QtCore/qpycore_classinfo.cpp
--- PyQt4_gpl_x11-4.12.3/qpy/QtCore/qpycore_classinfo.cpp.me 2022-06-21 15:04:28.885197054 +0200
+++ PyQt4_gpl_x11-4.12.3/qpy/QtCore/qpycore_classinfo.cpp 2022-06-21 15:04:51.654741730 +0200
@@ -36,7 +36,7 @@ PyObject *qpycore_ClassInfo(const char *
// We need the frame we were called from, not the current one.
if (frame)
- frame = frame->f_back;
+ frame = PyFrame_GetBack(frame);
if (!frame)
{