diff --git a/Src/Newtonsoft.Json.Tests/JsonTextReaderTest.cs b/Src/Newtonsoft.Json.Tests/JsonTextReaderTest.cs
index afa1b790..85888b0f 100644
--- a/Src/Newtonsoft.Json.Tests/JsonTextReaderTest.cs
+++ b/Src/Newtonsoft.Json.Tests/JsonTextReaderTest.cs
@@ -3249,6 +3249,7 @@ null//comment
                 "Unexpected character encountered while parsing value: !. Path 'frameworks.dnxcore50.dependencies.['System.Xml.ReaderWriter'].source', line 6, position 21.");
         }
 
+#if !DNXCORE50
         [Test]
         [Ignore("Fix this next major version")]
         public void LinePositionOnNewLine()
@@ -3297,6 +3298,7 @@ null//comment
 
             Assert.IsFalse(r.Read());
         }
+#endif
     }
 
     public class ToggleReaderError : TextReader
diff --git a/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj b/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj
index 7e4c5052..95d3aaf9 100644
--- a/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj
+++ b/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj
@@ -335,6 +335,7 @@
     <Compile Include="TestObjects\WidgetId1.cs" />
     <Compile Include="TestObjects\WidgetIdJsonConverter.cs" />
     <Compile Include="TestObjects\WithEnums.cs" />
+    <Compile Include="Utilities\ConvertUtilsTests.cs" />
     <Compile Include="Utilities\ExpressionReflectionDelegateFactoryTests.cs" />
     <Compile Include="Utilities\DateTimeUtilsTests.cs" />
     <Compile Include="Utilities\DynamicReflectionDelegateFactoryTests.cs" />
diff --git a/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs b/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs
index b0696653..1451ab9b 100644
--- a/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs
+++ b/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs
@@ -181,6 +181,7 @@ namespace Newtonsoft.Json.Tests.Serialization
 }", strJsonMainClass);
         }
 
+#if !(PORTABLE || PORTABLE40 || NET20 || NET35)
         [Test]
         public void LargeIntegerAsString()
         {
@@ -199,6 +200,7 @@ namespace Newtonsoft.Json.Tests.Serialization
         {
             public string Blah { get; set; }
         }
+#endif
 
         [Test]
         public void CaseInsensitiveRequiredPropertyConstructorCreation()
diff --git a/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs b/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs
index dd684942..7f208254 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs
@@ -86,14 +86,14 @@ namespace Newtonsoft.Json.Serialization
                     if (property.DeclaringType != null && existingProperty.DeclaringType != null)
                     {
                         if (property.DeclaringType.IsSubclassOf(existingProperty.DeclaringType)
-                            || (existingProperty.DeclaringType.IsInterface && property.DeclaringType.ImplementInterface(existingProperty.DeclaringType)))
+                            || (existingProperty.DeclaringType.IsInterface() && property.DeclaringType.ImplementInterface(existingProperty.DeclaringType)))
                         {
                             // current property is on a derived class and hides the existing
                             Remove(existingProperty);
                             duplicateProperty = false;
                         }
                         if (existingProperty.DeclaringType.IsSubclassOf(property.DeclaringType)
-                            || (property.DeclaringType.IsInterface && existingProperty.DeclaringType.ImplementInterface(property.DeclaringType)))
+                            || (property.DeclaringType.IsInterface() && existingProperty.DeclaringType.ImplementInterface(property.DeclaringType)))
                         {
                             // current property is hidden by the existing so don't add it
                             return;
diff --git a/Src/Newtonsoft.Json/Utilities/TypeExtensions.cs b/Src/Newtonsoft.Json/Utilities/TypeExtensions.cs
index e4bd1149..8f511546 100644
--- a/Src/Newtonsoft.Json/Utilities/TypeExtensions.cs
+++ b/Src/Newtonsoft.Json/Utilities/TypeExtensions.cs
@@ -553,13 +553,12 @@ namespace Newtonsoft.Json.Utilities
 
         public static bool ImplementInterface(this Type type, Type interfaceType)
         {
-            for (Type currentType = type; currentType != null; currentType = currentType.BaseType)
+            for (Type currentType = type; currentType != null; currentType = currentType.BaseType())
             {
-                Type[] interfaces = currentType.GetInterfaces();
-
-                for (int i = 0; i < interfaces.Length; i++)
+                IEnumerable<Type> interfaces = currentType.GetInterfaces();
+                foreach (Type i in interfaces)
                 {
-                    if (interfaces[i] == interfaceType || (interfaces[i] != null && interfaces[i].ImplementInterface(interfaceType)))
+                    if (i == interfaceType || (i != null && i.ImplementInterface(interfaceType)))
                     {
                         return true;
                     }