diff --git a/Scripts/Node.cs b/Scripts/Node.cs
index 704e99d..b705627 100644
--- a/Scripts/Node.cs
+++ b/Scripts/Node.cs
@@ -52,7 +52,13 @@ namespace XNode {
             /// <summary> Allow connections where output value type is assignable from input value type (eg. Object --> ScriptableObject)</summary>
             InheritedInverse,
             /// <summary> Allow connections where output value type is assignable from input value or input value type is assignable from output value type</summary>
-            InheritedAny
+            InheritedAny,
+            /// <summary> Allow connections where input value type is castable from output value type. </summary>
+            Castable,
+            /// <summary> Allow connections where output value type is castable from input value type. </summary>
+            CastableInverse,
+            /// <summary> Allow connections where input value type is castable from output value type or output value type is castable from input value type. </summary>
+            CastableAny
         }
 
 #region Obsolete
diff --git a/Scripts/NodePort.cs b/Scripts/NodePort.cs
index 6bcc638..14c3b7d 100644
--- a/Scripts/NodePort.cs
+++ b/Scripts/NodePort.cs
@@ -279,6 +279,9 @@ namespace XNode {
             if (output.typeConstraint == XNode.Node.TypeConstraint.Strict && input.ValueType != output.ValueType) return false;
             if (output.typeConstraint == XNode.Node.TypeConstraint.InheritedInverse && !output.ValueType.IsAssignableFrom(input.ValueType)) return false;
             if (output.typeConstraint == XNode.Node.TypeConstraint.InheritedAny && !input.ValueType.IsAssignableFrom(output.ValueType) && !output.ValueType.IsAssignableFrom(input.ValueType)) return false;
+            if (output.typeConstraint == XNode.Node.TypeConstraint.Castable && !input.ValueType.IsCastableFrom(output.ValueType)) return false;
+            if (output.typeConstraint == XNode.Node.TypeConstraint.CastableInverse && !output.ValueType.IsCastableFrom(input.ValueType)) return false;
+            if (output.typeConstraint == XNode.Node.TypeConstraint.CastableAny && !input.ValueType.IsCastableFrom(output.ValueType) && !output.ValueType.IsCastableFrom(input.ValueType)) return false;
             // Success
             return true;
         }
diff --git a/Scripts/TypeExtensions.cs b/Scripts/TypeExtensions.cs
new file mode 100644
index 0000000..ae49c31
--- /dev/null
+++ b/Scripts/TypeExtensions.cs
@@ -0,0 +1,16 @@
+using System.Linq;
+using System.Reflection;
+
+public static class TypeExtensions
+{
+    /// <summary> Determines whether an instance of a specified type can be assigned to a variable of the current type. </summary>
+    public static bool IsCastableFrom(this Type to, Type from)
+    {
+        if ( to.IsAssignableFrom ( from ) )
+            return true;
+        return from.GetMethods ( BindingFlags.Public | BindingFlags.Static ).Any ( m =>
+        {
+            return m.ReturnType == to && ( m.Name == "op_Implicit" || m.Name == "op_Explicit" );
+        } );
+    }
+}