pythonnet
diff --git a/src/embed_tests/TestConverter.cs b/src/embed_tests/TestConverter.cs
@@ -1,12 +1,27 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
+
 using NUnit.Framework;
+
 using Python.Runtime;
 
+using PyRuntime = Python.Runtime.Runtime;
+
 namespace Python.EmbeddingTest
 {
     public class TestConverter
     {
+        static readonly Type[] _numTypes = new Type[]
+        {
+                typeof(short),
+                typeof(ushort),
+                typeof(int),
+                typeof(uint),
+                typeof(long),
+                typeof(ulong)
+        };
+
         [OneTimeSetUp]
         public void SetUp()
         {
@@ -47,6 +62,60 @@ public void TestConvertDoubleToManaged(
             Assert.IsTrue(((double) convertedValue).Equals(testValue));
         }
 
+        [Test]
+        public void CovertTypeError()
+        {
+            Type[] floatTypes = new Type[]
+            {
+                typeof(float),
+                typeof(double)
+            };
+            using (var s = new PyString("abc"))
+            {
+                foreach (var type in _numTypes.Union(floatTypes))
+                {
+                    object value;
+                    try
+                    {
+                        bool res = Converter.ToManaged(s.Handle, type, out value, true);
+                        Assert.IsFalse(res);
+                        var bo = Exceptions.ExceptionMatches(Exceptions.TypeError);
+                        Assert.IsTrue(Exceptions.ExceptionMatches(Exceptions.TypeError)
+                            || Exceptions.ExceptionMatches(Exceptions.ValueError));
+                    }
+                    finally
+                    {
+                        Exceptions.Clear();
+                    }
+                }
+            }
+        }
+
+        [Test]
+        public void ConvertOverflow()
+        {
+            using (var num = new PyLong(ulong.MaxValue))
+            {
+                IntPtr largeNum = PyRuntime.PyNumber_Add(num.Handle, num.Handle);
+                try
+                {
+                    object value;
+                    foreach (var type in _numTypes)
+                    {
+                        bool res = Converter.ToManaged(largeNum, type, out value, true);
+                        Assert.IsFalse(res);
+                        Assert.IsTrue(Exceptions.ExceptionMatches(Exceptions.OverflowError));
+                        Exceptions.Clear();
+                    }
+                }
+                finally
+                {
+                    Exceptions.Clear();
+                    PyRuntime.XDecref(largeNum);
+                }
+            }
+        }
+
         [Test]
         public void RawListProxy()
         {

diff --git a/src/runtime/NewReference.cs b/src/runtime/NewReference.cs
@@ -27,14 +27,18 @@ public PyObject MoveToPyObject()
             this.pointer = IntPtr.Zero;
             return result;
         }
+
         /// <summary>
         /// Removes this reference to a Python object, and sets it to <c>null</c>.
         /// </summary>
         public void Dispose()
         {
-            if (!this.IsNull())
-                Runtime.XDecref(this.pointer);
-            this.pointer = IntPtr.Zero;
+            if (this.IsNull())
+            {
+                return;
+            }
+            Runtime.XDecref(pointer);
+            pointer = IntPtr.Zero;
         }
 
         /// <summary>