diff --git a/src/Umbraco.Core/Services/ContentTypeServiceExtensions.cs b/src/Umbraco.Core/Services/ContentTypeServiceExtensions.cs
index 6b440c6b2c..16dc068a10 100644
--- a/src/Umbraco.Core/Services/ContentTypeServiceExtensions.cs
+++ b/src/Umbraco.Core/Services/ContentTypeServiceExtensions.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Umbraco.Core.Configuration;
 using Umbraco.Core.Models;
 
 namespace Umbraco.Core.Services
@@ -15,8 +16,6 @@ namespace Umbraco.Core.Services
             IContentTypeComposition source,
             IContentTypeComposition[] allContentTypes)
         {
-
-            if (source == null) throw new ArgumentNullException("source");
             //below is all ported from the old doc type editor and comes with the same weaknesses /insanity / magic
 
             // note: there are many sanity checks missing here and there ;-((
@@ -25,11 +24,14 @@ namespace Umbraco.Core.Services
             //    throw new Exception("A parent does not belong to a composition.");
 
             // find out if any content type uses this content type
-            var isUsing = allContentTypes.Where(x => x.ContentTypeComposition.Any(y => y.Id == source.Id)).ToArray();
-            if (isUsing.Length > 0)
+            if (source != null)
             {
-                //if already in use a composition, do not allow any composited types
-                return new List<IContentTypeComposition>();
+                var isUsing = allContentTypes.Where(x => x.ContentTypeComposition.Any(y => y.Id == source.Id)).ToArray();
+                if (isUsing.Length > 0)
+                {
+                    //if already in use a composition, do not allow any composited types
+                    return new List<IContentTypeComposition>();
+                }
             }
 
             // if it is not used then composition is possible
@@ -59,9 +61,9 @@ namespace Umbraco.Core.Services
             //    .Where(x => x != source.ParentId) // but not the parent
             //    .Distinct()
             //    .ToArray();
-
+            
             return list
-                .Where(x => x.Id != source.Id)
+                .Where(x => x.Id != (source != null ? source.Id : 0))
                 .OrderBy(x => x.Name)                
                 .ToList();
         }
diff --git a/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs b/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs
index 1f4523661a..8e6ba92994 100644
--- a/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs
+++ b/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs
@@ -92,56 +92,9 @@ namespace Umbraco.Web.Editors
                     throw new ArgumentOutOfRangeException("The entity type was not a content type");
             }
 
-            // note: there are many sanity checks missing here and there ;-((
-            // make sure once and for all
-            //if (allContentTypes.Any(x => x.ParentId > 0 && x.ContentTypeComposition.Any(y => y.Id == x.ParentId) == false))
-            //    throw new Exception("A parent does not belong to a composition.");
+            var filtered = Services.ContentTypeService.GetAvailableCompositeContentTypes(source, allContentTypes);
 
-            // find out if any content type uses this content type
-            var isUsing = allContentTypes.Where(x => x.ContentTypeComposition.Any(y => y.Id == contentTypeId)).ToArray();
-            if (isUsing.Length > 0)
-            {
-                //if already in use a composition, do not allow any composited types
-                return new List<EntityBasic>();
-            }
-
-            // if it is not used then composition is possible
-            // hashset guarantees unicity on Id
-            var list = new HashSet<IContentTypeComposition>(new DelegateEqualityComparer<IContentTypeComposition>(
-                (x, y) => x.Id == y.Id,
-                x => x.Id));
-
-            // usable types are those that are top-level
-            var usableContentTypes = allContentTypes
-                .Where(x => x.ContentTypeComposition.Any() == false).ToArray();
-            foreach (var x in usableContentTypes)
-                list.Add(x);
-
-            // indirect types are those that we use, directly or indirectly
-            var indirectContentTypes = GetIndirect(source).ToArray();
-            foreach (var x in indirectContentTypes)
-                list.Add(x);
-
-            if (UmbracoConfig.For.UmbracoSettings().Content.EnableInheritedDocumentTypes)
-            {
-                // get the ancestorIds via the parent
-                var ancestorIds = new int[0];
-                if (parentId > 0)
-                {
-                    var parent = allContentTypes.FirstOrDefault(x => x.Id == parentId);
-                    if (parent != null)
-                        ancestorIds = parent.Path.Split(',').Select(int.Parse).ToArray();
-                }
-
-                // add all ancestors as compositions (since they are implicitly "compositions" by inheritance and should
-                // be in the list even though they can't be deselected)
-                foreach (var x in allContentTypes)
-                    if (ancestorIds.Contains(x.Id))
-                        list.Add(x);
-            }
-            return list
-                .Where(x => x.Id != contentTypeId)
-                .OrderBy(x => x.Name)
+            return filtered
                 .Select(Mapper.Map<IContentTypeComposition, EntityBasic>)
                 .Select(x =>
                 {
@@ -151,32 +104,6 @@ namespace Umbraco.Web.Editors
                 .ToList();
         }
 
-        private static IEnumerable<IContentTypeComposition> GetIndirect(IContentTypeComposition ctype)
-        {
-            // hashset guarantees unicity on Id
-            var all = new HashSet<IContentTypeComposition>(new DelegateEqualityComparer<IContentTypeComposition>(
-                (x, y) => x.Id == y.Id,
-                x => x.Id));
-
-            var stack = new Stack<IContentTypeComposition>();
-
-            if (ctype != null)
-            {
-                foreach (var x in ctype.ContentTypeComposition)
-                    stack.Push(x);
-            }
-
-            while (stack.Count > 0)
-            {
-                var x = stack.Pop();
-                all.Add(x);
-                foreach (var y in x.ContentTypeComposition)
-                    stack.Push(y);
-            }
-
-            return all;
-        }
-
         /// <summary>
         /// Validates the composition and adds errors to the model state if any are found then throws an error response if there are errors
         /// </summary>