diff --git a/pymongo/database.py b/pymongo/database.py
index 8aae097f8..f92040759 100644
--- a/pymongo/database.py
+++ b/pymongo/database.py
@@ -368,7 +368,6 @@ class Database(common.BaseObject):
             '_uuid_subtype': uuid_subtype
         }
 
-
         extra_opts['read_preference'] = kwargs.pop(
             'read_preference',
             self.read_preference)
@@ -496,11 +495,10 @@ class Database(common.BaseObject):
             idle operations in the result
          """
         if include_all:
-            return self['$cmd.sys.inprog'].find_one({"$all":True})
+            return self['$cmd.sys.inprog'].find_one({"$all": True})
         else:
             return self['$cmd.sys.inprog'].find_one()
 
-
     def profiling_level(self):
         """Get the database's current profiling level.
 
@@ -602,12 +600,20 @@ class Database(common.BaseObject):
 
         .. versionadded:: 1.4
         """
-        pwd = helpers._password_digest(name, password)
-        self.system.users.update({"user": name},
-                                 {"user": name,
-                                  "pwd": pwd,
-                                  "readOnly": read_only},
-                                 upsert=True, safe=True)
+
+        user = self.system.users.find_one({"user": name}) or {"user": name}
+        user["pwd"] = helpers._password_digest(name, password)
+        user["readOnly"] = common.validate_boolean('read_only', read_only)
+
+        try:
+            self.system.users.save(user, safe=True)
+        except OperationFailure, e:
+            # First admin user add fails gle in MongoDB >= 2.1.2
+            # See SERVER-4225 for more information.
+            if 'login' in str(e):
+                pass
+            else:
+                raise
 
     def remove_user(self, name):
         """Remove user `name` from this :class:`Database`.
diff --git a/pymongo/helpers.py b/pymongo/helpers.py
index d4804b3d7..7add9e66e 100644
--- a/pymongo/helpers.py
+++ b/pymongo/helpers.py
@@ -150,6 +150,8 @@ def _password_digest(username, password):
     if not isinstance(password, basestring):
         raise TypeError("password must be an instance "
                         "of %s" % (basestring.__name__,))
+    if len(password) == 0:
+        raise TypeError("password can't be empty")
     if not isinstance(username, basestring):
         raise TypeError("username must be an instance "
                         "of %s" % (basestring.__name__,))
diff --git a/test/high_availability/test_ha.py b/test/high_availability/test_ha.py
index 762ef8cb5..3d9bc5e92 100644
--- a/test/high_availability/test_ha.py
+++ b/test/high_availability/test_ha.py
@@ -621,11 +621,7 @@ class TestReplicaSetAuth(unittest.TestCase):
                                       use_greenlets=use_greenlets)
 
         # Add an admin user to enable auth
-        try:
-            self.c.admin.add_user('admin', 'adminpass')
-        except:
-            # SERVER-4225
-            pass
+        self.c.admin.add_user('admin', 'adminpass')
         self.c.admin.authenticate('admin', 'adminpass')
 
         self.db = self.c.pymongo_ha_auth
diff --git a/test/test_connection.py b/test/test_connection.py
index 6ce6eb5fb..151cfe5b4 100644
--- a/test/test_connection.py
+++ b/test/test_connection.py
@@ -239,13 +239,7 @@ class TestConnection(unittest.TestCase):
 
         c.admin.system.users.remove({})
         c.pymongo_test.system.users.remove({})
-
-        try:
-            # First admin user add fails gle in MongoDB >= 2.1.2
-            # See SERVER-4225 for more information.
-            c.admin.add_user("admin", "pass")
-        except OperationFailure:
-            pass
+        c.admin.add_user("admin", "pass")
         c.admin.authenticate("admin", "pass")
         c.pymongo_test.add_user("user", "pass")
 
@@ -505,7 +499,7 @@ with get_connection() as connection:
 
     def assertRequestSocket(self, pool):
         self.assertTrue(isinstance(pool._get_request_state(), SocketInfo))
-        
+
     def test_with_start_request(self):
         conn = get_connection(auto_start_request=False)
         pool = conn._Connection__pool
@@ -544,7 +538,7 @@ with conn.start_request() as request:
             # Request has ended
             self.assertNoRequest(pool)
             self.assertDifferentSock(pool)
-    
+
     def test_auto_start_request(self):
         for bad_horrible_value in (None, 5, 'hi!'):
             self.assertRaises(
diff --git a/test/test_database.py b/test/test_database.py
index 35223491a..7630a3df6 100644
--- a/test/test_database.py
+++ b/test/test_database.py
@@ -34,6 +34,7 @@ from pymongo import (ALL,
 from pymongo.collection import Collection
 from pymongo.database import Database
 from pymongo.errors import (CollectionInvalid,
+                            ConfigurationError,
                             InvalidName,
                             OperationFailure)
 from pymongo.son_manipulator import (AutoReference,
@@ -289,6 +290,13 @@ class TestDatabase(unittest.TestCase):
         db = self.connection.pymongo_test
         db.system.users.remove({})
         db.remove_user("mike")
+
+        self.assertRaises(TypeError, db.add_user, "user", None)
+        self.assertRaises(TypeError, db.add_user, "user", '')
+        self.assertRaises(TypeError, db.add_user, "user", 'password', None)
+        self.assertRaises(ConfigurationError, db.add_user,
+                          "user", 'password', 'True')
+
         db.add_user("mike", "password")
 
         self.assertRaises(TypeError, db.authenticate, 5, "password")
diff --git a/test/test_threads.py b/test/test_threads.py
index 950472283..d61d44ec4 100644
--- a/test/test_threads.py
+++ b/test/test_threads.py
@@ -385,12 +385,7 @@ class BaseTestThreadsAuth(object):
             raise SkipTest("Authentication is not enabled on server")
         self.conn = conn
         self.conn.admin.system.users.remove({})
-        try:
-            # First admin user add fails gle in MongoDB >= 2.1.2
-            # See SERVER-4225 for more information.
-            self.conn.admin.add_user('admin-user', 'password')
-        except OperationFailure:
-            pass
+        self.conn.admin.add_user('admin-user', 'password')
         self.conn.admin.authenticate("admin-user", "password")
         self.conn.auth_test.system.users.remove({})
         self.conn.auth_test.add_user("test-user", "password")