diff --git a/Source/Meadow.Foundation.Core/Color.cs b/Source/Meadow.Foundation.Core/Color.cs
index 2db82ca3b1..39fe073c75 100644
--- a/Source/Meadow.Foundation.Core/Color.cs
+++ b/Source/Meadow.Foundation.Core/Color.cs
@@ -298,7 +298,6 @@ public static Color FromRgb(byte r, byte g, byte b)
             return FromRgba(r, g, b, 255);
         }
 
-        /*
         public static Color FromRgba(double r, double g, double b, double a)
         {
             return new Color((byte)(r*255), (byte)(g * 255), (byte)(b * 255), (byte)(a * 255));
@@ -308,7 +307,6 @@ public static Color FromRgb(double r, double g, double b)
         {
             return FromRgba(r, g, b, 1f);
         }
-        */
 
         public static Color FromHsba(double h, double s, double b, double a = 1.0)
         {
diff --git a/Source/Meadow.Foundation.Core/Meadow.Foundation.Core.csproj b/Source/Meadow.Foundation.Core/Meadow.Foundation.Core.csproj
index a6049d1c59..8d7605a681 100644
--- a/Source/Meadow.Foundation.Core/Meadow.Foundation.Core.csproj
+++ b/Source/Meadow.Foundation.Core/Meadow.Foundation.Core.csproj
@@ -26,6 +26,7 @@
  <ItemGroup>
    <None Include="..\..\Source\icon.png" Pack="true" PackagePath="" />
    <ProjectReference Include="..\..\..\Meadow.Core\source\Meadow.Core\Meadow.Core.csproj" />
+   <ProjectReference Include="..\..\..\Meadow.Core\source\Meadow.Contracts\Meadow.Contracts.csproj" />
  </ItemGroup>
  <ItemGroup>
    <Folder Include="Displays\" />
diff --git a/Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Tca9548a/Driver/ICs.IOExpanders.TCA9548A/Tca9548A.cs b/Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Tca9548a/Driver/ICs.IOExpanders.TCA9548A/Tca9548A.cs
index d42a0d47ec..77ba7bc4dd 100644
--- a/Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Tca9548a/Driver/ICs.IOExpanders.TCA9548A/Tca9548A.cs
+++ b/Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Tca9548a/Driver/ICs.IOExpanders.TCA9548A/Tca9548A.cs
@@ -254,5 +254,10 @@ public void WriteRegister(byte address, Span<byte> writeBuffer, ByteOrder order
         {
             throw new NotImplementedException();
         }
+
+        public void Exchange(Span<byte> writeBuffer, Span<byte> readBuffer, DuplexType duplex)
+        {
+            throw new NotImplementedException();
+        }
     }
 }
\ No newline at end of file