diff --git a/Source/Cloning/ExpressionTreeCloner.PropertyBased.cs b/Source/Cloning/ExpressionTreeCloner.PropertyBased.cs
index f04d8b2..856487b 100644
--- a/Source/Cloning/ExpressionTreeCloner.PropertyBased.cs
+++ b/Source/Cloning/ExpressionTreeCloner.PropertyBased.cs
@@ -299,7 +299,6 @@ namespace Nuclex.Support.Cloning {
       variables.Add(clone);
 
       int dimensionCount = clonedType.GetArrayRank();
-      int baseVariableIndex = variables.Count;
       Type elementType = clonedType.GetElementType();
 
       var lengths = new List<ParameterExpression>();
diff --git a/Source/Cloning/ExpressionTreeCloner.cs b/Source/Cloning/ExpressionTreeCloner.cs
index 6f76f28..a17bd39 100644
--- a/Source/Cloning/ExpressionTreeCloner.cs
+++ b/Source/Cloning/ExpressionTreeCloner.cs
@@ -263,13 +263,21 @@ namespace Nuclex.Support.Cloning {
     }
 
     /// <summary>Compiled cloners that perform shallow clone operations</summary>
-    private static ConcurrentDictionary<Type, Func<object, object>> shallowFieldBasedCloners;
+    private static readonly ConcurrentDictionary<
+      Type, Func<object, object>
+    > shallowFieldBasedCloners;
     /// <summary>Compiled cloners that perform deep clone operations</summary>
-    private static ConcurrentDictionary<Type, Func<object, object>> deepFieldBasedCloners;
+    private static readonly ConcurrentDictionary<
+      Type, Func<object, object>
+    > deepFieldBasedCloners;
     /// <summary>Compiled cloners that perform shallow clone operations</summary>
-    private static ConcurrentDictionary<Type, Func<object, object>> shallowPropertyBasedCloners;
+    private static readonly ConcurrentDictionary<
+      Type, Func<object, object>
+    > shallowPropertyBasedCloners;
     /// <summary>Compiled cloners that perform deep clone operations</summary>
-    private static ConcurrentDictionary<Type, Func<object, object>> deepPropertyBasedCloners;
+    private static readonly ConcurrentDictionary<
+      Type, Func<object, object>
+    > deepPropertyBasedCloners;
 
   }
 
diff --git a/Source/Cloning/SerializationCloner.cs b/Source/Cloning/SerializationCloner.cs
index 5ac6e33..24698dc 100644
--- a/Source/Cloning/SerializationCloner.cs
+++ b/Source/Cloning/SerializationCloner.cs
@@ -92,7 +92,7 @@ namespace Nuclex.Support.Cloning {
       }
 
       /// <summary>Surrogate the that will be selected for any non-primitive types</summary>
-      private ISerializationSurrogate staticSurrogate;
+      private readonly ISerializationSurrogate staticSurrogate;
       /// <summary>Surrogate selector to escalate to if no surrogate can be provided</summary>
       private ISurrogateSelector chainedSelector;
 
@@ -321,9 +321,9 @@ namespace Nuclex.Support.Cloning {
     }
 
     /// <summary>Serializes objects by storing their fields</summary>
-    private static BinaryFormatter fieldBasedFormatter;
+    private static readonly BinaryFormatter fieldBasedFormatter;
     /// <summary>Serializes objects by storing their properties</summary>
-    private static BinaryFormatter propertyBasedFormatter;
+    private static readonly BinaryFormatter propertyBasedFormatter;
 
   }