diff --git a/plugins/User/plugin.py b/plugins/User/plugin.py
index 5cc50e693..8eb0d72e3 100644
--- a/plugins/User/plugin.py
+++ b/plugins/User/plugin.py
@@ -356,6 +356,7 @@ class User(callbacks.Plugin):
             try:
                 ircdb.users.setUser(user)
             except ircdb.DuplicateHostmask:
+                user.removeHostmask(hostmask)
                 irc.error(_('That hostmask is already registered.'),
                           Raise=True)
             except ValueError as e:
diff --git a/plugins/User/test.py b/plugins/User/test.py
index 850c6c02b..85b0987d0 100644
--- a/plugins/User/test.py
+++ b/plugins/User/test.py
@@ -38,8 +38,8 @@ import supybot.utils as utils
 
 class UserTestCase(PluginTestCase):
     plugins = ('User', 'Admin', 'Config')
-    prefix1 = 'somethingElse!user@host.tld'
-    prefix2 = 'EvensomethingElse!user@host.tld'
+    prefix1 = 'somethingElse!user@host1.tld'
+    prefix2 = 'EvensomethingElse!user@host2.tld'
 
     def testHostmaskList(self):
         self.assertError('hostmask list')
@@ -60,6 +60,21 @@ class UserTestCase(PluginTestCase):
         self.assertNotError('identify foo bar')
         self.assertRegexp('hostmask list', 'no registered hostmasks')
 
+    def testHostmaskOverlap(self):
+        self.assertNotError('register foo passwd', frm=self.prefix1)
+        self.assertNotError('register bar passwd', frm=self.prefix2)
+        self.assertResponse('whoami', 'foo', frm=self.prefix1)
+        self.assertResponse('whoami', 'bar', frm=self.prefix2)
+        self.assertNotError('hostmask add foo *!*@foobar/b',
+                frm=self.prefix1)
+        self.assertResponse('hostmask add bar *!*@foobar/*',
+                'Error: That hostmask is already registered.',
+                frm=self.prefix2)
+        self.assertRegexp('hostmask list foo', '\*!\*@foobar/b',
+                frm=self.prefix1)
+        self.assertNotRegexp('hostmask list bar', 'foobar',
+                frm=self.prefix2)
+
 
     def testHostmask(self):
         self.assertResponse('hostmask', self.prefix)