diff -r 074e12441ed6 -r bfa360f841cf Modules/_hashopenssl.c
--- a/Modules/_hashopenssl.c	Tue Mar 13 19:48:37 2012 -0700
+++ b/Modules/_hashopenssl.c	Thu Mar 15 16:35:08 2012 +0800
@@ -516,7 +516,7 @@
     if (py_name == NULL) {
         state->error = 1;
     } else {
-        if (PySet_Add(state->set, py_name) != 0) {
+        if (PySet_Add(state->set, py_name) == -1) {
             Py_DECREF(py_name);
             state->error = 1;
         }
diff -r 074e12441ed6 -r bfa360f841cf Objects/setobject.c
--- a/Objects/setobject.c	Tue Mar 13 19:48:37 2012 -0700
+++ b/Objects/setobject.c	Thu Mar 15 16:35:08 2012 +0800
@@ -226,17 +226,19 @@
         entry->key = key;
         entry->hash = hash;
         so->used++;
+        return 1;
     } else if (entry->key == dummy) {
         /* DUMMY */
         entry->key = key;
         entry->hash = hash;
         so->used++;
         Py_DECREF(dummy);
+        return 1;
     } else {
         /* ACTIVE */
         Py_DECREF(key);
+        return 0;
     }
-    return 0;
 }
 
 /*
@@ -361,29 +363,35 @@
 /* CAUTION: set_add_key/entry() must guarantee it won't resize the table */
 
 static int
-set_add_entry(register PySetObject *so, setentry *entry)
-{
+set_add_key_hash(register PySetObject *so, PyObject *key, Py_hash_t hash)
+{ 
     register Py_ssize_t n_used;
-    PyObject *key = entry->key;
-    Py_hash_t hash = entry->hash;
 
     assert(so->fill <= so->mask);  /* at least one empty slot */
     n_used = so->used;
     Py_INCREF(key);
-    if (set_insert_key(so, key, hash) == -1) {
+    int ret = set_insert_key(so, key, hash);
+    if (ret == -1) {
         Py_DECREF(key);
         return -1;
     }
     if (!(so->used > n_used && so->fill*3 >= (so->mask+1)*2))
-        return 0;
-    return set_table_resize(so, so->used>50000 ? so->used*2 : so->used*4);
+        return ret;
+    if (-1 == set_table_resize(so, so->used>50000 ? so->used*2 : so->used*4))
+        return -1;
+    return ret;
+}
+
+static int
+set_add_entry(register PySetObject *so, setentry *entry)
+{
+    return set_add_key_hash(so, entry->key, entry->hash);
 }
 
 static int
 set_add_key(register PySetObject *so, PyObject *key)
 {
-    register Py_hash_t hash;
-    register Py_ssize_t n_used;
+    Py_hash_t hash;
 
     if (!PyUnicode_CheckExact(key) ||
         (hash = ((PyASCIIObject *) key)->hash) == -1) {
@@ -391,16 +399,7 @@
         if (hash == -1)
             return -1;
     }
-    assert(so->fill <= so->mask);  /* at least one empty slot */
-    n_used = so->used;
-    Py_INCREF(key);
-    if (set_insert_key(so, key, hash) == -1) {
-        Py_DECREF(key);
-        return -1;
-    }
-    if (!(so->used > n_used && so->fill*3 >= (so->mask+1)*2))
-        return 0;
-    return set_table_resize(so, so->used>50000 ? so->used*2 : so->used*4);
+    return set_add_key_hash(so, key, hash);
 }
 
 #define DISCARD_NOTFOUND 0
@@ -408,7 +407,8 @@
 
 static int
 set_discard_entry(PySetObject *so, setentry *oldentry)
-{       register setentry *entry;
+{  
+    register setentry *entry;
     PyObject *old_key;
 
     entry = (so->lookup)(so, oldentry->key, oldentry->hash);
@@ -935,11 +935,7 @@
                 return -1;
         }
         while (_PyDict_Next(other, &pos, &key, &value, &hash)) {
-            setentry an_entry;
-
-            an_entry.hash = hash;
-            an_entry.key = key;
-            if (set_add_entry(so, &an_entry) == -1)
+            if (set_add_key_hash(so, key, hash) == -1)
                 return -1;
         }
         return 0;
@@ -1557,11 +1553,8 @@
 
     if (PyDict_CheckExact(other)) {
         while (set_next(so, &pos, &entry)) {
-            setentry entrycopy;
-            entrycopy.hash = entry->hash;
-            entrycopy.key = entry->key;
             if (!_PyDict_Contains(other, entry->key, entry->hash)) {
-                if (set_add_entry((PySetObject *)result, &entrycopy) == -1) {
+                if (set_add_key_hash((PySetObject *)result, entry->key, entry->hash) == -1) {
                     Py_DECREF(result);
                     return NULL;
                 }
@@ -1836,9 +1829,16 @@
 static PyObject *
 set_add(PySetObject *so, PyObject *key)
 {
-    if (set_add_key(so, key) == -1)
+    switch (set_add_key(so, key)) {
+    case 1:
+        Py_RETURN_TRUE;
+    case 0:
+        Py_RETURN_FALSE;
+    default:
+        PyErr_BadInternalCall();
+    case -1:
         return NULL;
-    Py_RETURN_NONE;
+    }
 }
 
 PyDoc_STRVAR(add_doc,
@@ -2403,7 +2403,7 @@
     elem = PySet_Pop(ob);
     assert(PySet_Contains(ob, elem) == 0);
     assert(PySet_GET_SIZE(ob) == 2);
-    assert(PySet_Add(ob, elem) == 0);
+    assert(PySet_Add(ob, elem) != -1);
     assert(PySet_Contains(ob, elem) == 1);
     assert(PySet_GET_SIZE(ob) == 3);
     assert(PySet_Discard(ob, elem) == 1);
@@ -2421,7 +2421,7 @@
     f = PyFrozenSet_New(dup);
     assertRaises(PySet_Clear(f) == -1, PyExc_SystemError);
     assertRaises(_PySet_Update(f, dup) == -1, PyExc_SystemError);
-    assert(PySet_Add(f, elem) == 0);
+    assert(PySet_Add(f, elem) != -1);
     Py_INCREF(f);
     assertRaises(PySet_Add(f, elem) == -1, PyExc_SystemError);
     Py_DECREF(f);
diff -r 074e12441ed6 -r bfa360f841cf Python/ceval.c
--- a/Python/ceval.c	Tue Mar 13 19:48:37 2012 -0700
+++ b/Python/ceval.c	Thu Mar 15 16:35:08 2012 +0800
@@ -1612,7 +1612,7 @@
             v = stack_pointer[-oparg];
             err = PySet_Add(v, w);
             Py_DECREF(w);
-            if (err == 0) {
+            if (err >= 0) {
                 PREDICT(JUMP_ABSOLUTE);
                 DISPATCH();
             }
@@ -2230,7 +2230,7 @@
                         err = PySet_Add(x, w);
                     Py_DECREF(w);
                 }
-                if (err != 0) {
+                if (err < 0) {
                     Py_DECREF(x);
                     break;
                 }