diff --git a/Bonobo.Git.Server/Data/Update/ADBackend/UpdateADBackend.cs b/Bonobo.Git.Server/Data/Update/ADBackend/UpdateADBackend.cs
index c289c121f..fc6512616 100644
--- a/Bonobo.Git.Server/Data/Update/ADBackend/UpdateADBackend.cs
+++ b/Bonobo.Git.Server/Data/Update/ADBackend/UpdateADBackend.cs
@@ -176,6 +176,12 @@ private static void UpdateRoles(string dir, Dictionary<string, Models.UserModel>
                 var members = new List<Guid>();
                 foreach (var memberName in role.Members)
                 {
+                    if (memberName == null)
+                    {
+                        Log.Warning("Role {0} in file {1} contained member with value \"null\". Skipping this member.", role.Name, dir);
+                        continue;
+                    }
+
                     Models.UserModel user;
                     if (users.TryGetValue(memberName, out user))
                     {