diff --git a/gnuviechadmin/osusers/models.py b/gnuviechadmin/osusers/models.py
index 5d5b586..68167cb 100644
--- a/gnuviechadmin/osusers/models.py
+++ b/gnuviechadmin/osusers/models.py
@@ -468,6 +468,8 @@ class SshPublicKeyManager(models.Manager):
         except TypeError:
             raise ValueError('invalid SSH public key')
         parts = keybytes.split(b'\x00' * 3)
+        if len(parts) < 2:
+            raise ValueError('invalid SSH public key')
         alglength = six.byte2int(parts[1])
         algname = parts[1][1:1+alglength]
         return algname, data, comment
diff --git a/gnuviechadmin/osusers/tests/test_models.py b/gnuviechadmin/osusers/tests/test_models.py
index 50ed035..bb8d5c9 100644
--- a/gnuviechadmin/osusers/tests/test_models.py
+++ b/gnuviechadmin/osusers/tests/test_models.py
@@ -1,3 +1,5 @@
+# -*- coding: utf8 -*-
+from __future__ import unicode_literals
 from datetime import date
 
 from django.conf import settings
@@ -91,6 +93,19 @@ n24VYtYtsMu74qXviYjziVucWKjjKEb11juqnF0GDlB3VVmxHLmxnAz643WK42Z7dLM5
 sY29ouezv4Xz2PuMch5VGPP+CDqzCM4loWgV
 ---- END SSH2 PUBLIC KEY ----"""
 
+EXAMPLE_KEY_7_NO_COMMENT = """---- BEGIN SSH2 PUBLIC KEY ----
+AAAAB3NzaC1yc2EAAAABIwAAAIEA1on8gxCGJJWSRT4uOrR13mUaUk0hRf4RzxSZ1zRb
+YYFw8pfGesIFoEuVth4HKyF8k1y4mRUnYHP1XNMNMJl1JcEArC2asV8sHf6zSPVffozZ
+5TT4SfsUu/iKy9lUcCfXzwre4WWZSXXcPff+EHtWshahu3WzBdnGxm5Xoi89zcE=
+---- END SSH2 PUBLIC KEY ----"""
+
+EXAMPLE_KEY_8_OPENSSH_BROKEN = "".join((
+    "ssh-rsa ",
+    "AschrÖdderöd"
+))
+
+EXAMPLE_KEY_9_RFC4716_ONLY_HEADER = "---- BEGIN SSH2 PUBLIC KEY ----"
+
 Customer = get_user_model()
 
 
@@ -135,6 +150,13 @@ class AdditionalGroupTest(TestCaseWithCeleryTasks):
                 (1, 'handle_user_added_to_group')]:
             self.assertEqual(creators.count(tcreator), tcount)
 
+    def test_save_again(self):
+        group2 = Group.objects.create(groupname='test2', gid=1001)
+        TaskResult.objects.all().delete()
+        group2.save()
+        taskres = TaskResult.objects.all()
+        self.assertEqual(len(taskres), 0)
+
     def test_delete(self):
         group2 = Group.objects.create(groupname='test2', gid=1001)
         addgroup = AdditionalGroup.objects.create(user=self.user, group=group2)
@@ -442,7 +464,7 @@ class SshPublicKeyManagerTest(TestCaseWithCeleryTasks):
         self.assertGreater(len(res[1]), 40)
         self.assertEqual(res[2], '')
 
-    def test_parse_keytext_invalid(self):
+    def test_parse_keytext_invalid_multiline(self):
         with self.assertRaises(ValueError):
             SshPublicKey.objects.parse_keytext("\r\n".join(["xx"]*10))
 
@@ -454,6 +476,19 @@ class SshPublicKeyManagerTest(TestCaseWithCeleryTasks):
         self.assertGreater(len(res[1]), 40)
         self.assertEqual(res[2], "DSA Public Key for use with MyIsp")
 
+    def test_parse_keytext_invalid_empty_rfc4716_header(self):
+        with self.assertRaises(ValueError):
+            SshPublicKey.objects.parse_keytext(
+                EXAMPLE_KEY_9_RFC4716_ONLY_HEADER)
+
+    def test_parse_keytext_no_comment(self):
+        res = SshPublicKey.objects.parse_keytext(
+            EXAMPLE_KEY_7_NO_COMMENT)
+        self.assertEqual(len(res), 3)
+        self.assertEqual(res[0], 'ssh-rsa')
+        self.assertGreater(len(res[1]), 40)
+        self.assertEqual(res[2], '')
+
     def test_parse_keytext_multiline_comment(self):
         res = SshPublicKey.objects.parse_keytext(
             EXAMPLE_KEY_5_RFC4716_MULTILINE)
@@ -462,6 +497,14 @@ class SshPublicKeyManagerTest(TestCaseWithCeleryTasks):
         self.assertGreater(len(res[1]), 40)
         self.assertEqual(res[2], "DSA Public Key for use with MyIsp")
 
+    def test_parse_keytext_invalid(self):
+        with self.assertRaises(ValueError):
+            SshPublicKey.objects.parse_keytext('invalid')
+
+    def test_parse_keytext_invalid_openssh(self):
+        with self.assertRaises(ValueError):
+            SshPublicKey.objects.parse_keytext(EXAMPLE_KEY_8_OPENSSH_BROKEN)
+
     def test_create_ssh_public_key(self):
         customer = Customer.objects.create_user('test')
         user = User.objects.create_user(customer)