diff --git a/Include/object.h b/Include/object.h
--- a/Include/object.h
+++ b/Include/object.h
@@ -706,7 +706,6 @@ PyAPI_DATA(Py_ssize_t) _Py_RefTotal;
 PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname,
                                             int lineno, PyObject *op);
 PyAPI_FUNC(PyObject *) _PyDict_Dummy(void);
-PyAPI_FUNC(PyObject *) _PySet_Dummy(void);
 PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void);
 #define _Py_INC_REFTOTAL        _Py_RefTotal++
 #define _Py_DEC_REFTOTAL        _Py_RefTotal--
diff --git a/Include/setobject.h b/Include/setobject.h
--- a/Include/setobject.h
+++ b/Include/setobject.h
@@ -61,6 +61,10 @@ struct _setobject {
 PyAPI_DATA(PyTypeObject) PySet_Type;
 PyAPI_DATA(PyTypeObject) PyFrozenSet_Type;
 PyAPI_DATA(PyTypeObject) PySetIter_Type;
+#ifndef Py_LIMITED_API
+PyAPI_DATA(PyObject *) _PySet_Dummy;
+#endif
+
 
 /* Invariants for frozensets:
  *     data is immutable.
diff --git a/Objects/object.c b/Objects/object.c
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -22,7 +22,7 @@ Py_ssize_t
     o = _PyDict_Dummy();
     if (o != NULL)
         total -= o->ob_refcnt;
-    o = _PySet_Dummy();
+    o = _PySet_Dummy;
     if (o != NULL)
         total -= o->ob_refcnt;
     return total;
diff --git a/Objects/setobject.c b/Objects/setobject.c
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -29,15 +29,7 @@ set_key_error(PyObject *arg)
 #define PERTURB_SHIFT 5
 
 /* Object used as dummy key to fill deleted entries */
-static PyObject *dummy = NULL; /* Initialized by first call to make_new_set() */
-
-#ifdef Py_REF_DEBUG
-PyObject *
-_PySet_Dummy(void)
-{
-    return dummy;
-}
-#endif
+PyObject *_PySet_Dummy = NULL; /* Initialized by first call to make_new_set() */
 
 #define INIT_NONZERO_SET_SLOTS(so) do {                         \
     (so)->table = (so)->smalltable;                             \
@@ -108,9 +100,9 @@ set_lookkey(PySetObject *so, PyObject *k
         }
     }
 
-    freeslot = (entry->key == dummy) ? entry : NULL;
+    freeslot = (entry->key == _PySet_Dummy) ? entry : NULL;
 
-    /* In the loop, key == dummy is by far (factor of 100s)
+    /* In the loop, key == _PySet_Dummy is by far (factor of 100s)
        the least likely outcome, so test for that last. */
     for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
         i = i * 5 + perturb + 1;
@@ -140,7 +132,7 @@ set_lookkey(PySetObject *so, PyObject *k
                 return set_lookkey(so, key, hash);
             }
         }
-        if (entry->key == dummy && freeslot == NULL)
+        if (entry->key == _PySet_Dummy && freeslot == NULL)
             freeslot = entry;
     }
     return entry;
@@ -173,7 +165,7 @@ set_lookkey_unicode(PySetObject *so, PyO
     entry = &table[i];
     if (entry->key == NULL || entry->key == key)
         return entry;
-    if (entry->key == dummy)
+    if (entry->key == _PySet_Dummy)
         freeslot = entry;
     else {
         if (entry->hash == hash && unicode_eq(entry->key, key))
@@ -181,7 +173,7 @@ set_lookkey_unicode(PySetObject *so, PyO
         freeslot = NULL;
     }
 
-    /* In the loop, key == dummy is by far (factor of 100s) the
+    /* In the loop, key == _PySet_Dummy is by far (factor of 100s) the
        least likely outcome, so test for that last. */
     for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
         i = i * 5 + perturb + 1;
@@ -190,10 +182,10 @@ set_lookkey_unicode(PySetObject *so, PyO
             return freeslot == NULL ? entry : freeslot;
         if (entry->key == key
             || (entry->hash == hash
-            && entry->key != dummy
+            && entry->key != _PySet_Dummy
             && unicode_eq(entry->key, key)))
             return entry;
-        if (entry->key == dummy && freeslot == NULL)
+        if (entry->key == _PySet_Dummy && freeslot == NULL)
             freeslot = entry;
     }
     assert(0);          /* NOT REACHED */
@@ -220,12 +212,12 @@ set_insert_key(PySetObject *so, PyObject
         entry->key = key;
         entry->hash = hash;
         so->used++;
-    } else if (entry->key == dummy) {
+    } else if (entry->key == _PySet_Dummy) {
         /* DUMMY */
         entry->key = key;
         entry->hash = hash;
         so->used++;
-        Py_DECREF(dummy);
+        Py_DECREF(_PySet_Dummy);
     } else {
         /* ACTIVE */
         Py_DECREF(key);
@@ -332,7 +324,7 @@ set_table_resize(PySetObject *so, Py_ssi
 
     /* Copy the data over; this is refcount-neutral for active entries;
        dummy entries aren't copied over, of course */
-    dummy_entry = dummy;
+    dummy_entry = _PySet_Dummy;
     for (entry = oldtable; i > 0; entry++) {
         if (entry->key == NULL) {
             /* UNUSED */
@@ -340,7 +332,7 @@ set_table_resize(PySetObject *so, Py_ssi
         } else if (entry->key == dummy_entry) {
             /* DUMMY */
             --i;
-            assert(entry->key == dummy);
+            assert(entry->key == _PySet_Dummy);
             Py_DECREF(entry->key);
         } else {
             /* ACTIVE */
@@ -410,11 +402,11 @@ set_discard_entry(PySetObject *so, seten
     entry = (so->lookup)(so, oldentry->key, oldentry->hash);
     if (entry == NULL)
         return -1;
-    if (entry->key == NULL  ||  entry->key == dummy)
+    if (entry->key == NULL  ||  entry->key == _PySet_Dummy)
         return DISCARD_NOTFOUND;
     old_key = entry->key;
-    Py_INCREF(dummy);
-    entry->key = dummy;
+    Py_INCREF(_PySet_Dummy);
+    entry->key = _PySet_Dummy;
     so->used--;
     Py_DECREF(old_key);
     return DISCARD_FOUND;
@@ -438,11 +430,11 @@ set_discard_key(PySetObject *so, PyObjec
     entry = (so->lookup)(so, key, hash);
     if (entry == NULL)
         return -1;
-    if (entry->key == NULL  ||  entry->key == dummy)
+    if (entry->key == NULL  ||  entry->key == _PySet_Dummy)
         return DISCARD_NOTFOUND;
     old_key = entry->key;
-    Py_INCREF(dummy);
-    entry->key = dummy;
+    Py_INCREF(_PySet_Dummy);
+    entry->key = _PySet_Dummy;
     so->used--;
     Py_DECREF(old_key);
     return DISCARD_FOUND;
@@ -537,7 +529,7 @@ set_next(PySetObject *so, Py_ssize_t *po
     assert(i >= 0);
     table = so->table;
     mask = so->mask;
-    while (i <= mask && (table[i].key == NULL || table[i].key == dummy))
+    while (i <= mask && (table[i].key == NULL || table[i].key == _PySet_Dummy))
         i++;
     *pos_ptr = i+1;
     if (i > mask)
@@ -652,7 +644,7 @@ set_merge(PySetObject *so, PyObject *oth
         key = entry->key;
         hash = entry->hash;
         if (key != NULL &&
-            key != dummy) {
+            key != _PySet_Dummy) {
             Py_INCREF(key);
             if (set_insert_key(so, key, hash) == -1) {
                 Py_DECREF(key);
@@ -679,7 +671,7 @@ set_contains_key(PySetObject *so, PyObje
     if (entry == NULL)
         return -1;
     key = entry->key;
-    return key != NULL && key != dummy;
+    return key != NULL && key != _PySet_Dummy;
 }
 
 static int
@@ -692,7 +684,7 @@ set_contains_entry(PySetObject *so, sete
     if (lu_entry == NULL)
         return -1;
     key = lu_entry->key;
-    return key != NULL && key != dummy;
+    return key != NULL && key != _PySet_Dummy;
 }
 
 static PyObject *
@@ -708,14 +700,14 @@ set_pop(PySetObject *so)
         return NULL;
     }
 
-    /* Set entry to "the first" unused or dummy set entry.  We abuse
+    /* Set entry to "the first" unused or _PySet_Dummy set entry.  We abuse
      * the hash field of slot 0 to hold a search finger:
      * If slot 0 has a value, use slot 0.
      * Else slot 0 is being used to hold a search finger,
      * and we use its hash value as the first index to look.
      */
     entry = &so->table[0];
-    if (entry->key == NULL || entry->key == dummy) {
+    if (entry->key == NULL || entry->key == _PySet_Dummy) {
         i = entry->hash;
         /* The hash field may be a real hash value, or it may be a
          * legit search finger, or it may be a once-legit search
@@ -724,15 +716,15 @@ set_pop(PySetObject *so)
          */
         if (i > so->mask || i < 1)
             i = 1;              /* skip slot 0 */
-        while ((entry = &so->table[i])->key == NULL || entry->key==dummy) {
+        while ((entry = &so->table[i])->key == NULL || entry->key==_PySet_Dummy) {
             i++;
             if (i > so->mask)
                 i = 1;
         }
     }
     key = entry->key;
-    Py_INCREF(dummy);
-    entry->key = dummy;
+    Py_INCREF(_PySet_Dummy);
+    entry->key = _PySet_Dummy;
     so->used--;
     so->table[0].hash = i + 1;  /* next place to start */
     return key;
@@ -885,7 +877,7 @@ static PyObject *setiter_iternext(setite
     assert(i>=0);
     entry = so->table;
     mask = so->mask;
-    while (i <= mask && (entry[i].key == NULL || entry[i].key == dummy))
+    while (i <= mask && (entry[i].key == NULL || entry[i].key == _PySet_Dummy))
         i++;
     si->si_pos = i+1;
     if (i > mask)
@@ -1023,9 +1015,9 @@ make_new_set(PyTypeObject *type, PyObjec
 {
     PySetObject *so = NULL;
 
-    if (dummy == NULL) { /* Auto-initialize dummy */
-        dummy = _PyObject_New(&PyBaseObject_Type);
-        if (dummy == NULL)
+    if (_PySet_Dummy == NULL) { /* Auto-initialize _PySet_Dummy */
+        _PySet_Dummy = _PyObject_New(&PyBaseObject_Type);
+        if (_PySet_Dummy == NULL)
             return NULL;
     }
 
@@ -1125,7 +1117,7 @@ void
 PySet_Fini(void)
 {
     PySet_ClearFreeList();
-    Py_CLEAR(dummy);
+    Py_CLEAR(_PySet_Dummy);
     Py_CLEAR(emptyfrozenset);
 }
 
diff --git a/Tools/gdb/libpython.py b/Tools/gdb/libpython.py
--- a/Tools/gdb/libpython.py
+++ b/Tools/gdb/libpython.py
@@ -963,20 +963,19 @@ class PySetObjectPtr(PyObjectPtr):
             out.write(tp_name)
             out.write('(')
 
+        dummy_ptr = gdb.lookup_global_symbol('_PySet_Dummy').value()
         out.write('{')
         first = True
         table = self.field('table')
         for i in safe_range(self.field('mask')+1):
             setentry = table[i]
             key = setentry['key']
-            if key != 0:
+            if key != 0 and key != dummy_ptr:
                 pyop_key = PyObjectPtr.from_pyobject_ptr(key)
-                key_proxy = pyop_key.proxyval(visited) # FIXME!
-                if key_proxy != '<dummy key>':
-                    if not first:
-                        out.write(', ')
-                    first = False
-                    pyop_key.write_repr(out, visited)
+                if not first:
+                    out.write(', ')
+                first = False
+                pyop_key.write_repr(out, visited)
         out.write('}')
 
         if tp_name != 'set':