diff --git a/src/Z.Core/System.Object/Convert/Object.ToOrDefault.cs b/src/Z.Core/System.Object/Convert/Object.ToOrDefault.cs
index f585bf06..255bcf7e 100644
--- a/src/Z.Core/System.Object/Convert/Object.ToOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/Object.ToOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 using System.ComponentModel;
 
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToBooleanOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToBooleanOrDefault.cs
index 211d1a06..aacc87ec 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToBooleanOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToBooleanOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static bool ToBooleanOrDefault(this object @this, bool defaultValue)
     {
         try
         {
-            return Convert.ToBoolean(@this);
+            return Convert.ToBoolean(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static bool ToBooleanOrDefault(this object @this, Func<bool> defaultValue
     {
         try
         {
-            return Convert.ToBoolean(@this);
+            return Convert.ToBoolean(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToByteOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToByteOrDefault.cs
index 9dc2e2c3..99efb6bd 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToByteOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToByteOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static byte ToByteOrDefault(this object @this, byte defaultValue)
     {
         try
         {
-            return Convert.ToByte(@this);
+            return Convert.ToByte(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static byte ToByteOrDefault(this object @this, Func<byte> defaultValueFac
     {
         try
         {
-            return Convert.ToByte(@this);
+            return Convert.ToByte(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToCharOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToCharOrDefault.cs
index cfbfdf19..5b0be046 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToCharOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToCharOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static char ToCharOrDefault(this object @this, char defaultValue)
     {
         try
         {
-            return Convert.ToChar(@this);
+            return Convert.ToChar(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static char ToCharOrDefault(this object @this, Func<char> defaultValueFac
     {
         try
         {
-            return Convert.ToChar(@this);
+            return Convert.ToChar(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOffSetOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOffSetOrDefault.cs
index c0dfd821..1a10eb86 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOffSetOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOffSetOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static DateTimeOffset ToDateTimeOffSetOrDefault(this object @this, DateTi
     {
         try
         {
-            return new DateTimeOffset(Convert.ToDateTime(@this), TimeSpan.Zero);
+            return new DateTimeOffset(Convert.ToDateTime(@this ?? ""), TimeSpan.Zero);
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static DateTimeOffset ToDateTimeOffSetOrDefault(this object @this, Func<D
     {
         try
         {
-            return new DateTimeOffset(Convert.ToDateTime(@this), TimeSpan.Zero);
+            return new DateTimeOffset(Convert.ToDateTime(@this ?? ""), TimeSpan.Zero);
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOrDefault.cs
index a02c1acf..bb49dbaa 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDateTimeOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static DateTime ToDateTimeOrDefault(this object @this, DateTime defaultVa
     {
         try
         {
-            return Convert.ToDateTime(@this);
+            return Convert.ToDateTime(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static DateTime ToDateTimeOrDefault(this object @this, Func<DateTime> def
     {
         try
         {
-            return Convert.ToDateTime(@this);
+            return Convert.ToDateTime(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDecimalOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDecimalOrDefault.cs
index c5e7e014..8d6d0fd1 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDecimalOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDecimalOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static decimal ToDecimalOrDefault(this object @this, decimal defaultValue
     {
         try
         {
-            return Convert.ToDecimal(@this);
+            return Convert.ToDecimal(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static decimal ToDecimalOrDefault(this object @this, Func<decimal> defaul
     {
         try
         {
-            return Convert.ToDecimal(@this);
+            return Convert.ToDecimal(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDoubleOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDoubleOrDefault.cs
index 543eb83c..272d3696 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDoubleOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToDoubleOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static double ToDoubleOrDefault(this object @this, double defaultValue)
     {
         try
         {
-            return Convert.ToDouble(@this);
+            return Convert.ToDouble(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static double ToDoubleOrDefault(this object @this, Func<double> defaultVa
     {
         try
         {
-            return Convert.ToDouble(@this);
+            return Convert.ToDouble(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToFloatOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToFloatOrDefault.cs
index 2a0c7656..1edf943d 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToFloatOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToFloatOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static float ToFloatOrDefault(this object @this, float defaultValue)
     {
         try
         {
-            return Convert.ToSingle(@this);
+            return Convert.ToSingle(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static float ToFloatOrDefault(this object @this, Func<float> defaultValue
     {
         try
         {
-            return Convert.ToSingle(@this);
+            return Convert.ToSingle(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToGuidOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToGuidOrDefault.cs
index 763ac9b0..ba603b76 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToGuidOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToGuidOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt16OrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt16OrDefault.cs
index 10d3ca44..14bdae57 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt16OrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt16OrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static short ToInt16OrDefault(this object @this, short defaultValue)
     {
         try
         {
-            return Convert.ToInt16(@this);
+            return Convert.ToInt16(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static short ToInt16OrDefault(this object @this, Func<short> defaultValue
     {
         try
         {
-            return Convert.ToInt16(@this);
+            return Convert.ToInt16(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt32OrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt32OrDefault.cs
index 62519158..e288cf07 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt32OrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt32OrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static int ToInt32OrDefault(this object @this, int defaultValue)
     {
         try
         {
-            return Convert.ToInt32(@this);
+            return Convert.ToInt32(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static int ToInt32OrDefault(this object @this, Func<int> defaultValueFact
     {
         try
         {
-            return Convert.ToInt32(@this);
+            return Convert.ToInt32(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt64OrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt64OrDefault.cs
index 0b4b520d..43de5235 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt64OrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToInt64OrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static long ToInt64OrDefault(this object @this, long defaultValue)
     {
         try
         {
-            return Convert.ToInt64(@this);
+            return Convert.ToInt64(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static long ToInt64OrDefault(this object @this, Func<long> defaultValueFa
     {
         try
         {
-            return Convert.ToInt64(@this);
+            return Convert.ToInt64(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToLongOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToLongOrDefault.cs
index 7e3f41cc..62f59a28 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToLongOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToLongOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static long ToLongOrDefault(this object @this, long defaultValue)
     {
         try
         {
-            return Convert.ToInt64(@this);
+            return Convert.ToInt64(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static long ToLongOrDefault(this object @this, Func<long> defaultValueFac
     {
         try
         {
-            return Convert.ToInt64(@this);
+            return Convert.ToInt64(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToNullableBooleanOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToNullableBooleanOrDefault.cs
index 20faf0c0..c0479151 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToNullableBooleanOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToNullableBooleanOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSByteOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSByteOrDefault.cs
index e696e323..15a4fe44 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSByteOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSByteOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static sbyte ToSByteOrDefault(this object @this, sbyte defaultValue)
     {
         try
         {
-            return Convert.ToSByte(@this);
+            return Convert.ToSByte(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static sbyte ToSByteOrDefault(this object @this, Func<sbyte> defaultValue
     {
         try
         {
-            return Convert.ToSByte(@this);
+            return Convert.ToSByte(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToShortOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToShortOrDefault.cs
index c3751f30..34ea1bd2 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToShortOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToShortOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static short ToShortOrDefault(this object @this, short defaultValue)
     {
         try
         {
-            return Convert.ToInt16(@this);
+            return Convert.ToInt16(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static short ToShortOrDefault(this object @this, Func<short> defaultValue
     {
         try
         {
-            return Convert.ToInt16(@this);
+            return Convert.ToInt16(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSingleOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSingleOrDefault.cs
index f6ae7312..d734bce4 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSingleOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToSingleOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static float ToSingleOrDefault(this object @this, float defaultValue)
     {
         try
         {
-            return Convert.ToSingle(@this);
+            return Convert.ToSingle(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static float ToSingleOrDefault(this object @this, Func<float> defaultValu
     {
         try
         {
-            return Convert.ToSingle(@this);
+            return Convert.ToSingle(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToStringOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToStringOrDefault.cs
index ec1df75a..edbf5578 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToStringOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToStringOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt16OrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt16OrDefault.cs
index ddbf6c36..6482c9fd 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt16OrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt16OrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static ushort ToUInt16OrDefault(this object @this, ushort defaultValue)
     {
         try
         {
-            return Convert.ToUInt16(@this);
+            return Convert.ToUInt16(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static ushort ToUInt16OrDefault(this object @this, Func<ushort> defaultVa
     {
         try
         {
-            return Convert.ToUInt16(@this);
+            return Convert.ToUInt16(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt32OrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt32OrDefault.cs
index e640c2a0..0bebb6ca 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt32OrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt32OrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static uint ToUInt32OrDefault(this object @this, uint defaultValue)
     {
         try
         {
-            return Convert.ToUInt32(@this);
+            return Convert.ToUInt32(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static uint ToUInt32OrDefault(this object @this, Func<uint> defaultValueF
     {
         try
         {
-            return Convert.ToUInt32(@this);
+            return Convert.ToUInt32(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt64OrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt64OrDefault.cs
index 8ff5b0c7..a6ea3199 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt64OrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUInt64OrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static ulong ToUInt64OrDefault(this object @this, ulong defaultValue)
     {
         try
         {
-            return Convert.ToUInt64(@this);
+            return Convert.ToUInt64(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static ulong ToUInt64OrDefault(this object @this, Func<ulong> defaultValu
     {
         try
         {
-            return Convert.ToUInt64(@this);
+            return Convert.ToUInt64(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToULongOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToULongOrDefault.cs
index 5b6c55a0..0a226834 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToULongOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToULongOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static ulong ToULongOrDefault(this object @this, ulong defaultValue)
     {
         try
         {
-            return Convert.ToUInt64(@this);
+            return Convert.ToUInt64(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static ulong ToULongOrDefault(this object @this, Func<ulong> defaultValue
     {
         try
         {
-            return Convert.ToUInt64(@this);
+            return Convert.ToUInt64(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUShortOrDefault.cs b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUShortOrDefault.cs
index b17bcab6..5178942d 100644
--- a/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUShortOrDefault.cs
+++ b/src/Z.Core/System.Object/Convert/ToValueType/Object.ToUShortOrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using System;
 
 public static partial class Extensions
@@ -35,7 +35,7 @@ public static ushort ToUShortOrDefault(this object @this, ushort defaultValue)
     {
         try
         {
-            return Convert.ToUInt16(@this);
+            return Convert.ToUInt16(@this ?? "");
         }
         catch (Exception)
         {
@@ -53,7 +53,7 @@ public static ushort ToUShortOrDefault(this object @this, Func<ushort> defaultVa
     {
         try
         {
-            return Convert.ToUInt16(@this);
+            return Convert.ToUInt16(@this ?? "");
         }
         catch (Exception)
         {
diff --git a/test/Z.Core.Test/System.Object/Object.ToInt32OrDefault.cs b/test/Z.Core.Test/System.Object/Object.ToInt32OrDefault.cs
index 592a9cf4..3d58a841 100644
--- a/test/Z.Core.Test/System.Object/Object.ToInt32OrDefault.cs
+++ b/test/Z.Core.Test/System.Object/Object.ToInt32OrDefault.cs
@@ -3,7 +3,7 @@
 // Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
 // License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
 // More projects: http://www.zzzprojects.com/
-// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+// Copyright ?ZZZ Projects Inc. 2014 - 2016. All rights reserved.
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
 namespace Z.Core.Test
@@ -17,6 +17,8 @@ public void ToInt32OrDefault()
             // Type
             string @thisValid = "32";
             string @thisInvalid = "FizzBuzz";
+            string @thisNull = null;
+            string @thisEmpty = "";
 
             // Exemples
             int result1 = @thisValid.ToInt32OrDefault(); // return 32;
@@ -24,6 +26,9 @@ public void ToInt32OrDefault()
             int result3 = @thisInvalid.ToInt32OrDefault(-1); // return -1;
             int result4 = @thisInvalid.ToInt32OrDefault(() => -2); // return -2;
 
+            int result5 = @thisNull.ToInt32OrDefault(-1);
+            int result6 = thisEmpty.ToInt32OrDefault(-1);
+
             // Unit Test
             Assert.AreEqual(32, result1);
             Assert.AreEqual(0, result2);