diff --git a/Tools/gdb/libpython.py b/Tools/gdb/libpython.py
--- a/Tools/gdb/libpython.py
+++ b/Tools/gdb/libpython.py
@@ -935,7 +935,7 @@
             key = setentry['key']
             if key != 0:
                 key_proxy = PyObjectPtr.from_pyobject_ptr(key).proxyval(visited)
-                if key_proxy != '<dummy key>':
+                if repr(key_proxy) != '<dummy key>':
                     members.append(key_proxy)
         if self.safe_tp_name() == 'frozenset':
             return frozenset(members)