diff --git a/Perspex.Animation/PropertyTransitions.cs b/Perspex.Animation/PropertyTransitions.cs
index 1bb91b18f1..bf251404d4 100644
--- a/Perspex.Animation/PropertyTransitions.cs
+++ b/Perspex.Animation/PropertyTransitions.cs
@@ -8,6 +8,8 @@ using Perspex.Collections;
 
 namespace Perspex.Animation
 {
+    using Perspex.Collections;
+
     public class PropertyTransitions : PerspexList<PropertyTransition>
     {
     }
diff --git a/Perspex.Base/Perspex.Base.csproj b/Perspex.Base/Perspex.Base.csproj
index 70631febbb..1ddb527ce9 100644
--- a/Perspex.Base/Perspex.Base.csproj
+++ b/Perspex.Base/Perspex.Base.csproj
@@ -36,14 +36,14 @@
   <ItemGroup>
     <Compile Include="Binding.cs" />
     <Compile Include="Collections\IPerspexList.cs" />
-    <Compile Include="Collections\IReadOnlyPerspexList.cs" />
     <Compile Include="Collections\PerspexList.cs" />
-    <Compile Include="Collections\PerspexListExtensions.cs" />
     <Compile Include="Collections\SingleItemPerspexList.cs" />
     <Compile Include="Contract.cs" />
     <Compile Include="Diagnostics\PerspexPropertyValue.cs" />
     <Compile Include="IDescription.cs" />
+    <Compile Include="Collections\PerspexListExtensions.cs" />
     <Compile Include="IObservableDescription.cs" />
+    <Compile Include="Collections\IReadOnlyPerspexList.cs" />
     <Compile Include="PerspexObject.cs" />
     <Compile Include="PerspexProperty.cs" />
     <Compile Include="PerspexPropertyChangedEventArgs.cs" />
diff --git a/Perspex.Controls/ColumnDefinitions.cs b/Perspex.Controls/ColumnDefinitions.cs
index 0dc5a1834a..636db00c36 100644
--- a/Perspex.Controls/ColumnDefinitions.cs
+++ b/Perspex.Controls/ColumnDefinitions.cs
@@ -8,6 +8,8 @@ using Perspex.Collections;
 
 namespace Perspex.Controls
 {
+    using Perspex.Collections;
+
     public class ColumnDefinitions : PerspexList<ColumnDefinition>
     {
     }
diff --git a/Perspex.Controls/DataTemplates.cs b/Perspex.Controls/DataTemplates.cs
index 42a1a17182..7de64339ed 100644
--- a/Perspex.Controls/DataTemplates.cs
+++ b/Perspex.Controls/DataTemplates.cs
@@ -6,13 +6,6 @@
 
 namespace Perspex.Controls
 {
-    using System;
-    using System.Collections;
-    using System.Collections.Generic;
-    using System.Collections.Specialized;
-    using System.Linq;
-    using System.Reactive;
-    using System.Reactive.Subjects;
     using Perspex.Collections;
 
     public class DataTemplates : PerspexList<DataTemplate>
diff --git a/Perspex.SceneGraph/IVisual.cs b/Perspex.SceneGraph/IVisual.cs
index 24dee5fc20..72a38d1703 100644
--- a/Perspex.SceneGraph/IVisual.cs
+++ b/Perspex.SceneGraph/IVisual.cs
@@ -6,7 +6,6 @@
 
 namespace Perspex
 {
-    using System.Collections.Generic;
     using Perspex.Collections;
     using Perspex.Media;