diff -r 177e0254fdee Objects/setobject.c
--- a/Objects/setobject.c	Tue Nov 19 11:06:44 2013 -0500
+++ b/Objects/setobject.c	Tue Nov 19 10:14:31 2013 -0800
@@ -1749,11 +1749,25 @@
 static PyObject *
 set_issubset(PySetObject *so, PyObject *other)
 {
-    setentry *entry;
-    Py_ssize_t pos = 0;
+    int rv;
+    PyObject *tmp, *result;
 
-    if (!PyAnySet_Check(other)) {
-        PyObject *tmp, *result;
+    if (PyAnySet_Check(other)) {
+        if (PySet_GET_SIZE(so) > PySet_GET_SIZE(other))
+            Py_RETURN_FALSE;
+
+        setentry *entry;
+        Py_ssize_t pos = 0;
+        while (set_next(so, &pos, &entry)) {
+            rv = set_contains_entry((PySetObject *)other, entry);
+            if (rv == -1)
+                return NULL;
+            if (!rv)
+                Py_RETURN_FALSE;
+        }
+    }
+
+    else if (PyDict_CheckExact(other)) {
         tmp = make_new_set(&PySet_Type, other);
         if (tmp == NULL)
             return NULL;
@@ -1761,16 +1775,52 @@
         Py_DECREF(tmp);
         return result;
     }
-    if (PySet_GET_SIZE(so) > PySet_GET_SIZE(other))
+
+    else {
+        PyObject *key, *it;
+
+        tmp = make_new_set(&PySet_Type, NULL);
+        if (tmp == NULL)
+            return NULL;
+
+        it = PyObject_GetIter(other);
+        if (it == NULL) {
+            Py_DECREF(tmp);
+            return NULL;
+        }
+
+        int n = so->used;
+        while ((key = PyIter_Next(it)) != NULL) {
+            setentry entry;
+            Py_hash_t hash = PyObject_Hash(key);
+            if (hash == -1) {
+                Py_DECREF(it);
+                Py_DECREF(tmp);
+                Py_DECREF(key);
+                return NULL;
+            }
+            entry.hash = hash;
+            entry.key = key;
+            rv = set_add_entry((PySetObject *)tmp, &entry);
+            Py_DECREF(key);
+            if (rv == -1) {
+                continue;
+            }
+            if (set_contains_entry(so, &entry) == 1 && !(--n)) {
+                Py_DECREF(it);
+                Py_DECREF(tmp);
+                Py_RETURN_TRUE;
+            }
+        }
+
+        Py_DECREF(it);
+        Py_DECREF(tmp);
+        if (PyErr_Occurred())
+            return NULL;
+
         Py_RETURN_FALSE;
+    }
 
-    while (set_next(so, &pos, &entry)) {
-        int rv = set_contains_entry((PySetObject *)other, entry);
-        if (rv == -1)
-            return NULL;
-        if (!rv)
-            Py_RETURN_FALSE;
-    }
     Py_RETURN_TRUE;
 }