diff --git a/Context/Factories/GameObjectFactory.cs b/Context/Factories/GameObjectFactory.cs
index 551c88f..a8cde2b 100644
--- a/Context/Factories/GameObjectFactory.cs
+++ b/Context/Factories/GameObjectFactory.cs
@@ -42,7 +42,7 @@ namespace Svelto.Context
         /// Register a prefab to be built later using a string ID.
         /// </summary>
         /// <param name="prefab">original prefab</param>
-        public GameObject Build(GameObject prefab)
+        virtual public GameObject Build(GameObject prefab)
         {
             var copy = Object.Instantiate(prefab) as GameObject;
 
diff --git a/Context/Factories/MonoBehaviourFactory.cs b/Context/Factories/MonoBehaviourFactory.cs
index 62502f6..94786dd 100644
--- a/Context/Factories/MonoBehaviourFactory.cs
+++ b/Context/Factories/MonoBehaviourFactory.cs
@@ -10,11 +10,7 @@ namespace Svelto.Context
 {
     public class MonoBehaviourFactory : Factories.IMonoBehaviourFactory
     {
-        public MonoBehaviourFactory()
-        {
-        }
-
-        public M Build<M>(Func<M> constructor) where M : MonoBehaviour
+        virtual public M Build<M>(Func<M> constructor) where M : MonoBehaviour
         {
             var mb = constructor();
 
diff --git a/DataStructures/FasterList.cs b/DataStructures/FasterList.cs
index 78cbaa2..ae44d60 100644
--- a/DataStructures/FasterList.cs
+++ b/DataStructures/FasterList.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Threading;
 using UnityEngine;
 
 namespace Svelto.DataStructures
@@ -188,6 +189,183 @@ namespace Svelto.DataStructures
         readonly FasterList<T> _list;
     }
 
+    public struct FasterListThreadSafe<T> : IList<T>
+    {
+        public FasterListThreadSafe(FasterList<T> list)
+        {
+            _list = list;
+            _lockQ = new ReaderWriterLockSlim();
+        }
+
+        public int Count
+        {
+            get
+            {
+                _lockQ.EnterReadLock();
+                try
+                {
+                    return _list.Count;
+                }
+                finally
+                {
+                    _lockQ.ExitReadLock();
+                }
+            }
+        }
+        public bool IsReadOnly { get { return false; } }
+
+        public T this[int index]
+        {
+            get
+            {
+                _lockQ.EnterReadLock();
+                try
+                {
+                    return _list[index];
+                }
+                finally
+                {
+                    _lockQ.ExitReadLock();
+                }
+            }
+            set
+            {
+                _lockQ.EnterWriteLock();
+                try
+                {
+                    _list[index] = value;
+                }
+                finally
+                {
+                    _lockQ.ExitWriteLock();
+                }
+            }
+        }
+
+        public FasterListEnumerator<T> GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        public void Add(T item)
+        {
+            _lockQ.EnterWriteLock();
+            try
+            {
+                _list.Add(item);
+            }
+            finally
+            {
+                _lockQ.ExitWriteLock();
+            }
+        }
+
+        public void Clear()
+        {
+            _lockQ.EnterWriteLock();
+            try
+            {
+                _list.Clear();
+            }
+            finally
+            {
+                _lockQ.ExitWriteLock();
+            }
+        }
+
+        public bool Contains(T item)
+        {
+            _lockQ.EnterReadLock();
+            try
+            {
+                return _list.Contains(item);
+            }
+            finally
+            {
+                _lockQ.ExitReadLock();
+            }
+        }
+
+        public void CopyTo(T[] array, int arrayIndex)
+        {
+            _lockQ.EnterWriteLock();
+            try
+            {
+                _list.CopyTo(array, arrayIndex);
+            }
+            finally
+            {
+                _lockQ.ExitWriteLock();
+            }
+        }
+
+        public bool Remove(T item)
+        {
+            _lockQ.EnterWriteLock();
+            try
+            {
+                return _list.Remove(item);
+            }
+            finally
+            {
+                _lockQ.ExitWriteLock();
+            }
+        }
+
+        public int IndexOf(T item)
+        {
+            _lockQ.EnterReadLock();
+            try
+            {
+                return _list.IndexOf(item);
+            }
+            finally
+            {
+                _lockQ.ExitReadLock();
+            }
+        }
+
+        public void Insert(int index, T item)
+        {
+            _lockQ.EnterWriteLock();
+            try
+            {
+                _list.Insert(index, item);
+            }
+            finally
+            {
+                _lockQ.ExitWriteLock();
+            }
+        }
+
+        public void RemoveAt(int index)
+        {
+            _lockQ.EnterWriteLock();
+            try
+            {
+                _list.RemoveAt(index);
+            }
+            finally
+            {
+                _lockQ.ExitWriteLock();
+            }
+        }
+
+        IEnumerator<T> IEnumerable<T>.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        readonly FasterList<T> _list;
+       
+        readonly ReaderWriterLockSlim _lockQ;
+    }
+
     public struct FasterReadOnlyListCast<T, U> : IList<U> where U:T
     {
         public static FasterList<T> DefaultList = new FasterList<T>();
@@ -320,6 +498,14 @@ namespace Svelto.DataStructures
             _buffer[_count++] = item;
         }
 
+
+        /// <summary>
+        /// this is a dirtish trick to be able to use the index operastor 
+        /// before adding the elements through the Add functions
+        /// </summary>
+        /// <typeparam name="U"></typeparam>
+        /// <param name="initialSize"></param>
+        /// <returns></returns>
         public static FasterList<T> PreFill<U>(int initialSize) where U:T, new()
         {
             var list = new FasterList<T>(initialSize);
diff --git a/DataStructures/ThreadSafeDictionary.cs b/DataStructures/ThreadSafeDictionary.cs
index 94a3646..1505547 100644
--- a/DataStructures/ThreadSafeDictionary.cs
+++ b/DataStructures/ThreadSafeDictionary.cs
@@ -1,7 +1,10 @@
+
 using System;
 using System.Collections.Generic;
 using System.Threading;
 
+//note, rewrite like ThreadSafeQueue
+
 namespace Svelto.DataStructures
 {
     /// <summary>
@@ -13,6 +16,16 @@ namespace Svelto.DataStructures
     [Serializable]
     public class ThreadSafeDictionary<TKey, TValue>
     {
+        public ThreadSafeDictionary(int v)
+        {
+            dict = new Dictionary<TKey, TValue>(v);
+        }
+
+        public ThreadSafeDictionary()
+        {
+            dict = new Dictionary<TKey, TValue>();
+        }
+
         // setup the lock;
         public virtual int Count
         {
@@ -183,7 +196,7 @@ namespace Svelto.DataStructures
         }
 
         // This is the internal dictionary that we are wrapping
-        readonly IDictionary<TKey, TValue> dict = new Dictionary<TKey, TValue>();
+        readonly IDictionary<TKey, TValue> dict;
 
         [NonSerialized] readonly ReaderWriterLockSlim dictionaryLock = Locks.GetLockInstance(LockRecursionPolicy.NoRecursion);
     }
diff --git a/DataStructures/ThreadSafeQueue.cs b/DataStructures/ThreadSafeQueue.cs
index 4505dd8..d9197f0 100644
--- a/DataStructures/ThreadSafeQueue.cs
+++ b/DataStructures/ThreadSafeQueue.cs
@@ -1,4 +1,3 @@
-using System.Collections;
 using System.Collections.Generic;
 using System.Threading;
 
@@ -6,9 +5,9 @@ namespace Svelto.DataStructures
 {
     public class ThreadSafeQueue<T>
     {
-        private readonly Queue<T> m_Queue;
+        readonly Queue<T> m_Queue;
 
-        private readonly ReaderWriterLockSlim LockQ = new ReaderWriterLockSlim();
+        readonly ReaderWriterLockSlim LockQ = new ReaderWriterLockSlim();
 
         public ThreadSafeQueue()
         {
@@ -121,6 +120,22 @@ namespace Svelto.DataStructures
             }
         }
 
+        public void DequeueInto(FasterList<T> list, int count)
+        {
+            LockQ.EnterWriteLock();
+            try
+            {
+                int originalSize = m_Queue.Count;
+                while (m_Queue.Count > 0 && originalSize - m_Queue.Count < count)
+                    list.Add(m_Queue.Dequeue());
+            }   
+
+            finally
+            {
+                LockQ.ExitWriteLock();
+            }
+        }
+
         public FasterList<U> DequeueAllAs<U>() where U:class
         {
             LockQ.EnterWriteLock();
diff --git a/ECS/Dispatcher/DispatcherOnChange.cs b/ECS/Dispatcher/DispatchOnChange.cs
similarity index 100%
rename from ECS/Dispatcher/DispatcherOnChange.cs
rename to ECS/Dispatcher/DispatchOnChange.cs
diff --git a/ECS/Dispatcher/DispatcherOnChange.cs.meta b/ECS/Dispatcher/DispatchOnChange.cs.meta
similarity index 100%
rename from ECS/Dispatcher/DispatcherOnChange.cs.meta
rename to ECS/Dispatcher/DispatchOnChange.cs.meta
diff --git a/ECS/EngineNodeDB.cs b/ECS/EngineNodeDB.cs
index 1ed8944..8c73fa2 100644
--- a/ECS/EngineNodeDB.cs
+++ b/ECS/EngineNodeDB.cs
@@ -94,6 +94,10 @@ namespace Svelto.ECS
         Dictionary<Type, Dictionary<int, INode>> _nodesDBdic;
         Dictionary<Type, FasterList<INode>>      _nodesDBgroups;
 
+        //Dictionary<Type, ThreadSafeFasterList<INode>>       _nodesDB;
+        //Dictionary<Type, ThreadsSafeDictionary<int, INode>> _nodesDBdic;
+//        Dictionary<Type, ThreadSafeFasterList<INode>>       _nodesDBgroups;
+
         ReadOnlyDictionary<int, INode> _defaultEmptyNodeDict = new ReadOnlyDictionary<int, INode>(new Dictionary<int, INode>());
     }
 }
diff --git a/ECS/EnginesRoot.cs b/ECS/EnginesRoot.cs
index 0f1867a..d3af55c 100644
--- a/ECS/EnginesRoot.cs
+++ b/ECS/EnginesRoot.cs
@@ -122,31 +122,32 @@ namespace Svelto.ECS
                 var nodesEngine = engine as INodesEngine;
 
                 AddEngine(nodesEngine, nodesEngine.AcceptedNodes(), _nodeEngines);
-
-                return;
             }
+            else
+            {
+
+                var engineType = engine.GetType();
+//                Type baseInterface = null;
+
 #if !NETFX_CORE
-            var baseType = engine.GetType().BaseType;
+                var baseType = engineType.BaseType;
 
-            if (baseType.IsGenericType)
+                if (baseType.IsGenericType
 #else
-            var baseType = engine.GetType().GetTypeInfo().BaseType;
+                var baseType = engineType.GetTypeInfo().BaseType;
 
-            if (baseType.IsConstructedGenericType)
+                if (baseType.IsConstructedGenericType
 #endif
-            
-            {
-                var genericType = baseType.GetGenericTypeDefinition();
-
-                if (genericType == typeof(SingleNodeEngine<>))
+                && baseType.GetGenericTypeDefinition() == typeof (SingleNodeEngine<>))
                 {
                     AddEngine(engine as INodeEngine<INode>, baseType.GetGenericArguments(), _nodeEngines);
-
-                    return;
                 }
+                else
+                    _otherEnginesReferences.Add(engine);
             }
-
-            _otherEnginesReferences.Add(engine);
+            
+            if (engine is ICallBackOnAddEngine)
+                (engine as ICallBackOnAddEngine).Ready();
         }
 
         public void BuildEntity(int ID, EntityDescriptor ed)
@@ -160,6 +161,19 @@ namespace Svelto.ECS
             _nodesToAdd.AddRange(entityNodes);
         }
 
+        /// <summary>
+        /// An entity group is a meta entity. It's a way to create a set of entitites that
+        /// are not easily queriable otherwise. For example you may group existing entities
+        /// by size and type and then use the groupID to retrieve a single node that is shared
+        /// among the single entities of the same type and size. This willwd prevent the scenario
+        /// where the coder is forced to parse all the entities to find the ones of the same
+        /// size and type. Since the entity group is managed through the shared node, the same
+        /// shared node must be found on the single entities of the same type and size.
+        /// The shared node is then used by engines that are meant to manage a group of entities
+        /// through a single node. The same engine can manage several groups of entitites.
+        /// </summary>
+        /// <param name="groupID"></param>
+        /// <param name="ed"></param>
         public void BuildEntityGroup(int groupID, EntityDescriptor ed)
         {
             var entityNodes = ed.BuildNodes(groupID, (node) =>
@@ -234,7 +248,7 @@ namespace Svelto.ECS
                 {
 #if ENGINE_PROFILER_ENABLED && UNITY_EDITOR
                     EngineProfiler.MonitorAddDuration(AddNodeToEngine, enginesForNode[j], node);
-#else 
+#else
                     enginesForNode[j].Add(node);
 #endif
                 }
@@ -280,7 +294,7 @@ namespace Svelto.ECS
                 {
 #if ENGINE_PROFILER_ENABLED && UNITY_EDITOR
                     EngineProfiler.MonitorRemoveDuration(RemoveNodeFromEngine, enginesForNode[j], node);
-#else 
+#else
                     enginesForNode[j].Remove(node);
 #endif
                 }
@@ -317,22 +331,15 @@ namespace Svelto.ECS
         Dictionary<Type, FasterList<INodeEngine<INode>>>     _nodeEngines;
         FasterList<IEngine>                                  _otherEnginesReferences;
 
-        Dictionary<Type, FasterList<INode>>                  _nodesDB;
-        Dictionary<Type, Dictionary<int, INode>>             _nodesDBdic;
-
-        Dictionary<Type, FasterList<INode>>                  _nodesDBgroups;
-
-        FasterList<INode>                                    _nodesToAdd;
-        FasterList<INode>                                    _groupNodesToAdd;
+        Dictionary<Type, FasterList<INode>>       _nodesDB;
+        Dictionary<Type, Dictionary<int, INode>>  _nodesDBdic;
 
-        WeakReference                                        _engineRootWeakReference;
+        Dictionary<Type, FasterList<INode>>       _nodesDBgroups;
 
-        //integrated pooling system
-        //add debug panel like Entitas has
-        //GCHandle should be used to reduce the number of strong references
-        //datastructure could be thread safe
+        FasterList<INode>                         _nodesToAdd;
+        FasterList<INode>                         _groupNodesToAdd;
 
-        //future enhancements:
+        WeakReference                             _engineRootWeakReference;
     }
 }
 
diff --git a/ECS/EntityDescriptor.cs b/ECS/EntityDescriptor.cs
index 6183fd5..7dab7ee 100644
--- a/ECS/EntityDescriptor.cs
+++ b/ECS/EntityDescriptor.cs
@@ -1,6 +1,9 @@
 using System;
 using System.Reflection;
 using Svelto.DataStructures;
+#if NETFX_CORE
+using BindingFlags = System.Reflection.BindingFlags;
+#endif
 
 namespace Svelto.ECS
 {
@@ -12,6 +15,16 @@ namespace Svelto.ECS
             _nodesToBuild = nodesToBuild;
         }
 
+        public void AddImplementors(params object[] componentsImplementor)
+        {
+            var implementors = new object[componentsImplementor.Length + _implementors.Length];
+
+            Array.Copy(_implementors, implementors, _implementors.Length);
+            Array.Copy(componentsImplementor, 0, implementors, _implementors.Length, componentsImplementor.Length);
+
+            _implementors = implementors;
+        }
+
         public virtual FasterList<INode> BuildNodes(int ID, Action<INode> removeAction)
         {
             var nodes = new FasterList<INode>();
@@ -73,8 +86,9 @@ namespace Svelto.ECS
             return node;
         }
 
-        readonly object[]   _implementors;
-        INodeBuilder[]      _nodesToBuild;
+        object[]       _implementors;
+
+        readonly INodeBuilder[] _nodesToBuild;
     }
 
     public interface INodeBuilder
diff --git a/ECS/GenericEntityDescriptor.cs b/ECS/GenericEntityDescriptor.cs
index 16c2687..62ddd73 100644
--- a/ECS/GenericEntityDescriptor.cs
+++ b/ECS/GenericEntityDescriptor.cs
@@ -5,14 +5,11 @@
     {
         static GenericEntityDescriptor()
         {
-            _nodesToBuild = new INodeBuilder[]
-            {
-                new NodeBuilder<T>()
-            };
+            _nodesToBuild = new INodeBuilder[] { new NodeBuilder<T>() };
         }
         public GenericEntityDescriptor(params object[] componentsImplementor) : base(_nodesToBuild, componentsImplementor)
-        {
-        }
+        {}
+
         static INodeBuilder[] _nodesToBuild;
     }
 
@@ -28,9 +25,10 @@
                 new NodeBuilder<U>()
             };
         }
+
         public GenericEntityDescriptor(params object[] componentsImplementor) : base(_nodesToBuild, componentsImplementor)
-        {
-        }
+        {}
+
         static INodeBuilder[] _nodesToBuild;
     }
 
diff --git a/ECS/GenericEntityDescriptorHolder.cs b/ECS/GenericEntityDescriptorHolder.cs
new file mode 100644
index 0000000..4758fa2
--- /dev/null
+++ b/ECS/GenericEntityDescriptorHolder.cs
@@ -0,0 +1,28 @@
+using System;
+
+namespace Svelto.ECS
+{
+    public class GenericEntityDescriptorHolder<T, I>: UnityEngine.MonoBehaviour, IEntityDescriptorHolder where T:EntityDescriptor
+    {
+        public EntityDescriptor BuildDescriptorType(object[] externalImplentors)
+        {
+            I[] implementors;
+
+            if (externalImplentors != null)
+            {
+                I[] baseImplentors = gameObject.GetComponents<I>();
+
+                implementors = new I[externalImplentors.Length + baseImplentors.Length];
+
+                Array.Copy(baseImplentors, implementors, baseImplentors.Length);
+                Array.Copy(externalImplentors, 0, implementors, baseImplentors.Length, externalImplentors.Length);
+            }
+            else
+            {
+                implementors = gameObject.GetComponents<I>();
+            }
+
+            return (T)Activator.CreateInstance(typeof(T), implementors);
+        }
+    }
+}
\ No newline at end of file
diff --git a/ECS/GenericEntityDescriptorHolder.cs.meta b/ECS/GenericEntityDescriptorHolder.cs.meta
new file mode 100644
index 0000000..fc5bfc6
--- /dev/null
+++ b/ECS/GenericEntityDescriptorHolder.cs.meta
@@ -0,0 +1,12 @@
+fileFormatVersion: 2
+guid: f2bc0783e8d4a7b49a84705c55d8b255
+timeCreated: 1498225965
+licenseType: Pro
+MonoImporter:
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/ECS/ICallBackOnAddEngine.cs b/ECS/ICallBackOnAddEngine.cs
new file mode 100644
index 0000000..30ac6de
--- /dev/null
+++ b/ECS/ICallBackOnAddEngine.cs
@@ -0,0 +1,7 @@
+namespace Svelto.ECS
+{
+    interface ICallBackOnAddEngine
+    {
+        void Ready();
+    }
+}
\ No newline at end of file
diff --git a/ECS/ICallBackOnAddEngine.cs.meta b/ECS/ICallBackOnAddEngine.cs.meta
new file mode 100644
index 0000000..80e5f96
--- /dev/null
+++ b/ECS/ICallBackOnAddEngine.cs.meta
@@ -0,0 +1,12 @@
+fileFormatVersion: 2
+guid: 3928de9a08e5b534ab857ea8b5bebdaf
+timeCreated: 1497524074
+licenseType: Pro
+MonoImporter:
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/ECS/Profiler/Editor/EngineProfiler/EngineProfilerInspector.cs b/ECS/Profiler/Editor/EngineProfiler/EngineProfilerInspector.cs
index 1ac387a..a691298 100644
--- a/ECS/Profiler/Editor/EngineProfiler/EngineProfilerInspector.cs
+++ b/ECS/Profiler/Editor/EngineProfiler/EngineProfilerInspector.cs
@@ -21,7 +21,6 @@ namespace Svelto.ECS.Profiler
         }
 
         static bool _hideEmptyEngines = true;
-        static bool _showTickEngines;
         static bool _showAddEngines;
         static bool _showRemoveEngines;
 
@@ -31,9 +30,6 @@ namespace Svelto.ECS.Profiler
         string maxTitle = "Max".PadRight(15, ' ');
         string avgTitle = "Avg".PadRight(15, ' ');
 
-        EnginesMonitor _enginesMonitor;
-        Queue<float> _engineMonitorData;
-        const int SYSTEM_MONITOR_DATA_LENGTH = 300;
         SORTING_OPTIONS _sortingOption = SORTING_OPTIONS.AVERAGE;
 
         public override void OnInspectorGUI()
diff --git a/ECS/Profiler/Editor/EngineProfiler/ProfilerEditorLayout.cs.meta b/ECS/Profiler/Editor/EngineProfiler/ProfilerEditorLayout.cs.meta
index 489305b..11f6ff4 100644
--- a/ECS/Profiler/Editor/EngineProfiler/ProfilerEditorLayout.cs.meta
+++ b/ECS/Profiler/Editor/EngineProfiler/ProfilerEditorLayout.cs.meta
@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 3e961e5c8cc40064fa25092d835d1a80
+guid: de0de03babf2e9d4db95c2be94eb8c95
 timeCreated: 1462527509
 licenseType: Pro
 MonoImporter:
diff --git a/ECS/SingleNodeEngine.cs b/ECS/SingleNodeEngine.cs
index f888ee2..6b43243 100644
--- a/ECS/SingleNodeEngine.cs
+++ b/ECS/SingleNodeEngine.cs
@@ -12,9 +12,7 @@
             Remove(obj as TNodeType);
         }
 
-        protected virtual void Add(TNodeType node)
-        {}
-        protected virtual void Remove(TNodeType node)
-        {}
+        protected abstract void Add(TNodeType node);
+        protected abstract void Remove(TNodeType node);
     }
 }
diff --git a/Utilities/WeakActionStruct.cs b/Utilities/WeakActionStruct.cs
index 8bb39b4..dff59f6 100644
--- a/Utilities/WeakActionStruct.cs
+++ b/Utilities/WeakActionStruct.cs
@@ -12,11 +12,16 @@ namespace BetterWeakEvents
         public WeakAction(Action<T1, T2> listener)
         {
             ObjectRef = GCHandle.Alloc(listener.Target, GCHandleType.Weak);
-
-#if !NETFX_CORE
-            Method = listener.Method;
-#else
+#if NETFX_CORE
             Method = listener.GetMethodInfo();
+            var attributes = (CompilerGeneratedAttribute[])Method.GetType().GetTypeInfo().GetCustomAttributes(typeof(CompilerGeneratedAttribute), false);
+            if(attributes.Length != 0)
+                throw new ArgumentException("Cannot create weak event to anonymous method with closure.");
+#else
+            Method = listener.Method;
+
+            if (Method.DeclaringType.GetCustomAttributes(typeof(CompilerGeneratedAttribute), false).Length != 0)
+                throw new ArgumentException("Cannot create weak event to anonymous method with closure.");
 #endif
         }
 
@@ -51,10 +56,16 @@ namespace BetterWeakEvents
         public WeakAction(Action<T> listener)
         {
             ObjectRef = GCHandle.Alloc(listener.Target, GCHandleType.Weak);
-#if !NETFX_CORE
-            Method = listener.Method;
-#else
+#if NETFX_CORE
             Method = listener.GetMethodInfo();
+            var attributes = (CompilerGeneratedAttribute[])Method.GetType().GetTypeInfo().GetCustomAttributes(typeof(CompilerGeneratedAttribute), false);
+            if(attributes.Length != 0)
+                throw new ArgumentException("Cannot create weak event to anonymous method with closure.");
+#else
+            Method = listener.Method;
+
+            if (Method.DeclaringType.GetCustomAttributes(typeof(CompilerGeneratedAttribute), false).Length != 0)
+                throw new ArgumentException("Cannot create weak event to anonymous method with closure.");
 #endif
         }
 
@@ -89,10 +100,16 @@ namespace BetterWeakEvents
         public WeakAction(Action listener)
         {
             ObjectRef = GCHandle.Alloc(listener.Target, GCHandleType.Weak);
-#if !NETFX_CORE
-            Method = listener.Method;
-#else
+#if NETFX_CORE
             Method = listener.GetMethodInfo();
+            var attributes = (CompilerGeneratedAttribute[])Method.GetType().GetTypeInfo().GetCustomAttributes(typeof(CompilerGeneratedAttribute), false);
+            if(attributes.Length != 0)
+                throw new ArgumentException("Cannot create weak event to anonymous method with closure.");
+#else
+            Method = listener.Method;
+
+            if (Method.DeclaringType.GetCustomAttributes(typeof(CompilerGeneratedAttribute), false).Length != 0)
+                throw new ArgumentException("Cannot create weak event to anonymous method with closure.");
 #endif
         }