diff --git a/src/Gui/PythonDebugger.cpp b/src/Gui/PythonDebugger.cpp
index f72bfcf19..fc7b432c8 100644
--- a/src/Gui/PythonDebugger.cpp
+++ b/src/Gui/PythonDebugger.cpp
@@ -360,6 +360,7 @@ struct PythonDebuggerP {
     }
     ~PythonDebuggerP()
     {
+        Base::PyGILStateLocker lock;
         Py_DECREF(out_n);
         Py_DECREF(err_n);
         Py_DECREF(exc_n);