diff -r c29301b1503f Lib/ssl.py
--- a/Lib/ssl.py	Fri Mar 21 21:49:38 2014 -0400
+++ b/Lib/ssl.py	Sat Mar 22 01:01:47 2014 -0400
@@ -517,6 +517,13 @@
                 raise ValueError("check_hostname requires server_hostname, "
                                  "but it's not supported by your OpenSSL "
                                  "library")
+
+        if server_side and not self._context._has_set_ecdh_curve:
+            if HAS_ECDH:
+                # This is a sever side socket and no ECDH curve has been
+                # specified
+                self._context.set_ecdh_curve()
+
         self.server_side = server_side
         self.server_hostname = server_hostname
         self.do_handshake_on_connect = do_handshake_on_connect
diff -r c29301b1503f Lib/test/test_ssl.py
--- a/Lib/test/test_ssl.py	Fri Mar 21 21:49:38 2014 -0400
+++ b/Lib/test/test_ssl.py	Sat Mar 22 01:01:47 2014 -0400
@@ -922,7 +922,6 @@
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
         ctx.set_ecdh_curve("prime256v1")
         ctx.set_ecdh_curve(b"prime256v1")
-        self.assertRaises(TypeError, ctx.set_ecdh_curve)
         self.assertRaises(TypeError, ctx.set_ecdh_curve, None)
         self.assertRaises(ValueError, ctx.set_ecdh_curve, "foo")
         self.assertRaises(ValueError, ctx.set_ecdh_curve, b"foo")
diff -r c29301b1503f Modules/_ssl.c
--- a/Modules/_ssl.c	Fri Mar 21 21:49:38 2014 -0400
+++ b/Modules/_ssl.c	Sat Mar 22 01:01:47 2014 -0400
@@ -213,6 +213,9 @@
     PyObject *set_hostname;
 #endif
     int check_hostname;
+#ifndef OPENSSL_NO_ECDH
+    int _has_set_ecdh_curve;
+#endif
 } PySSLContext;
 
 typedef struct {
@@ -2052,6 +2055,10 @@
 #endif
     /* Don't check host name by default */
     self->check_hostname = 0;
+#ifndef OPENSSL_NO_ECDH
+    /* We haven't set a ecdh curve yet */
+    self->_has_set_ecdh_curve = 0;
+#endif
     /* Defaults */
     SSL_CTX_set_verify(self->ctx, SSL_VERIFY_NONE, NULL);
     options = SSL_OP_ALL & ~SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS;
@@ -2337,6 +2344,14 @@
     return 0;
 }
 
+#ifndef OPENSSL_NO_ECDH
+static PyObject *
+get_has_set_ecdh_curve(PySSLContext *self, void *c)
+{
+    return PyBool_FromLong(self->_has_set_ecdh_curve);
+}
+#endif
+
 
 typedef struct {
     PyThreadState *thread_state;
@@ -2855,22 +2870,33 @@
 
 #ifndef OPENSSL_NO_ECDH
 static PyObject *
-set_ecdh_curve(PySSLContext *self, PyObject *name)
+set_ecdh_curve(PySSLContext *self, PyObject *args)
 {
+    PyObject *name = NULL;
     PyObject *name_bytes;
     int nid;
     EC_KEY *key;
 
-    if (!PyUnicode_FSConverter(name, &name_bytes))
-        return NULL;
-    assert(PyBytes_Check(name_bytes));
-    nid = OBJ_sn2nid(PyBytes_AS_STRING(name_bytes));
-    Py_DECREF(name_bytes);
-    if (nid == 0) {
-        PyErr_Format(PyExc_ValueError,
-                     "unknown elliptic curve name %R", name);
+    if (!PyArg_ParseTuple(args, "|O:name", &name)) {
         return NULL;
     }
+
+    if (name == NULL) {
+        nid = NID_X9_62_prime256v1;
+    }
+    else {
+        if (!PyUnicode_FSConverter(name, &name_bytes))
+            return NULL;
+        assert(PyBytes_Check(name_bytes));
+        nid = OBJ_sn2nid(PyBytes_AS_STRING(name_bytes));
+        Py_DECREF(name_bytes);
+        if (nid == 0) {
+            PyErr_Format(PyExc_ValueError,
+                         "unknown elliptic curve name %R", name);
+            return NULL;
+        }
+    }
+
     key = EC_KEY_new_by_curve_name(nid);
     if (key == NULL) {
         _setSSLError(NULL, 0, __FILE__, __LINE__);
@@ -2878,6 +2904,10 @@
     }
     SSL_CTX_set_tmp_ecdh(self->ctx, key);
     EC_KEY_free(key);
+
+    /* Mark that we've set a ecdh curve */
+    self->_has_set_ecdh_curve = 1;
+
     Py_RETURN_NONE;
 }
 #endif
@@ -3131,6 +3161,9 @@
                        (setter) set_check_hostname, NULL},
     {"options", (getter) get_options,
                 (setter) set_options, NULL},
+#ifndef OPENSSL_NO_ECDH
+    {"_has_set_ecdh_curve", (getter) get_has_set_ecdh_curve, NULL, NULL},
+#endif
 #ifdef HAVE_OPENSSL_VERIFY_PARAM
     {"verify_flags", (getter) get_verify_flags,
                      (setter) set_verify_flags, NULL},
@@ -3159,7 +3192,7 @@
                                  METH_NOARGS, NULL},
 #ifndef OPENSSL_NO_ECDH
     {"set_ecdh_curve", (PyCFunction) set_ecdh_curve,
-                       METH_O, NULL},
+                       METH_VARARGS, NULL},
 #endif
     {"set_servername_callback", (PyCFunction) set_servername_callback,
                     METH_VARARGS, PySSL_set_servername_callback_doc},