diff --git a/src/Weakly/Builders/CachingDynamicDelegateBuilderDecorator.cs b/src/Weakly/Builders/CachingDynamicDelegateBuilderDecorator.cs
index e5ce965..5c2255b 100644
--- a/src/Weakly/Builders/CachingDynamicDelegateBuilderDecorator.cs
+++ b/src/Weakly/Builders/CachingDynamicDelegateBuilderDecorator.cs
@@ -30,7 +30,7 @@ public CachingDynamicDelegateBuilderDecorator(IDynamicDelegateBuilder builder)
         public Func<object, object[], object> BuildDynamic(MethodInfo method)
         {
             var action = _cache.GetValueOrDefault(method);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildDynamic(method);
             _cache.AddOrUpdate(method, action);
             return action;
diff --git a/src/Weakly/Builders/CachingOpenActionBuilderDecorator.cs b/src/Weakly/Builders/CachingOpenActionBuilderDecorator.cs
index 7534c09..46c81f8 100644
--- a/src/Weakly/Builders/CachingOpenActionBuilderDecorator.cs
+++ b/src/Weakly/Builders/CachingOpenActionBuilderDecorator.cs
@@ -30,7 +30,7 @@ public CachingOpenActionBuilderDecorator(IOpenActionBuilder builder)
         public Action<object> BuildAction(MethodInfo method)
         {
             var action = (Action<object>) _cache.GetValueOrDefault(method);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildAction(method);
             _cache.AddOrUpdate(method, action);
             return action;
@@ -47,7 +47,7 @@ public Action<object> BuildAction(MethodInfo method)
         public Action<object, T> BuildAction<T>(MethodInfo method)
         {
             var action = (Action<object, T>) _cache.GetValueOrDefault(method);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildAction<T>(method);
             _cache.AddOrUpdate(method, action);
             return action;
@@ -65,7 +65,7 @@ public Action<object, T> BuildAction<T>(MethodInfo method)
         public Action<object, T1, T2> BuildAction<T1, T2>(MethodInfo method)
         {
             var action = (Action<object, T1, T2>) _cache.GetValueOrDefault(method);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildAction<T1, T2>(method);
             _cache.AddOrUpdate(method, action);
             return action;
@@ -84,7 +84,7 @@ public Action<object, T1, T2> BuildAction<T1, T2>(MethodInfo method)
         public Action<object, T1, T2, T3> BuildAction<T1, T2, T3>(MethodInfo method)
         {
             var action = (Action<object, T1, T2, T3>) _cache.GetValueOrDefault(method);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildAction<T1, T2, T3>(method);
             _cache.AddOrUpdate(method, action);
             return action;
@@ -104,7 +104,7 @@ public Action<object, T1, T2, T3> BuildAction<T1, T2, T3>(MethodInfo method)
         public Action<object, T1, T2, T3, T4> BuildAction<T1, T2, T3, T4>(MethodInfo method)
         {
             var action = (Action<object, T1, T2, T3, T4>) _cache.GetValueOrDefault(method);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildAction<T1, T2, T3, T4>(method);
             _cache.AddOrUpdate(method, action);
             return action;
@@ -125,7 +125,7 @@ public Action<object, T1, T2, T3, T4> BuildAction<T1, T2, T3, T4>(MethodInfo met
         public Action<object, T1, T2, T3, T4, T5> BuildAction<T1, T2, T3, T4, T5>(MethodInfo method)
         {
             var action = (Action<object, T1, T2, T3, T4, T5>) _cache.GetValueOrDefault(method);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildAction<T1, T2, T3, T4, T5>(method);
             _cache.AddOrUpdate(method, action);
             return action;
diff --git a/src/Weakly/Builders/CachingOpenFuncBuilderDecorator.cs b/src/Weakly/Builders/CachingOpenFuncBuilderDecorator.cs
index c46a12e..27855f5 100644
--- a/src/Weakly/Builders/CachingOpenFuncBuilderDecorator.cs
+++ b/src/Weakly/Builders/CachingOpenFuncBuilderDecorator.cs
@@ -31,7 +31,7 @@ public CachingOpenFuncBuilderDecorator(IOpenFuncBuilder builder)
         public Func<object, TResult> BuildFunc<TResult>(MethodInfo method)
         {
             var func = (Func<object, TResult>) _cache.GetValueOrDefault(method);
-            if (func != null) return func;
+            if (func is object) return func;
             func = _builder.BuildFunc<TResult>(method);
             _cache.AddOrUpdate(method, func);
             return func;
@@ -49,7 +49,7 @@ public Func<object, TResult> BuildFunc<TResult>(MethodInfo method)
         public Func<object, T, TResult> BuildFunc<T, TResult>(MethodInfo method)
         {
             var func = (Func<object, T, TResult>) _cache.GetValueOrDefault(method);
-            if (func != null) return func;
+            if (func is object) return func;
             func = _builder.BuildFunc<T, TResult>(method);
             _cache.AddOrUpdate(method, func);
             return func;
@@ -68,7 +68,7 @@ public Func<object, T, TResult> BuildFunc<T, TResult>(MethodInfo method)
         public Func<object, T1, T2, TResult> BuildFunc<T1, T2, TResult>(MethodInfo method)
         {
             var func = (Func<object, T1, T2, TResult>) _cache.GetValueOrDefault(method);
-            if (func != null) return func;
+            if (func is object) return func;
             func = _builder.BuildFunc<T1, T2, TResult>(method);
             _cache.AddOrUpdate(method, func);
             return func;
@@ -88,7 +88,7 @@ public Func<object, T1, T2, TResult> BuildFunc<T1, T2, TResult>(MethodInfo metho
         public Func<object, T1, T2, T3, TResult> BuildFunc<T1, T2, T3, TResult>(MethodInfo method)
         {
             var func = (Func<object, T1, T2, T3, TResult>) _cache.GetValueOrDefault(method);
-            if (func != null) return func;
+            if (func is object) return func;
             func = _builder.BuildFunc<T1, T2, T3, TResult>(method);
             _cache.AddOrUpdate(method, func);
             return func;
@@ -109,7 +109,7 @@ public Func<object, T1, T2, T3, TResult> BuildFunc<T1, T2, T3, TResult>(MethodIn
         public Func<object, T1, T2, T3, T4, TResult> BuildFunc<T1, T2, T3, T4, TResult>(MethodInfo method)
         {
             var func = (Func<object, T1, T2, T3, T4, TResult>) _cache.GetValueOrDefault(method);
-            if (func != null) return func;
+            if (func is object) return func;
             func = _builder.BuildFunc<T1, T2, T3, T4, TResult>(method);
             _cache.AddOrUpdate(method, func);
             return func;
@@ -131,7 +131,7 @@ public Func<object, T1, T2, T3, T4, TResult> BuildFunc<T1, T2, T3, T4, TResult>(
         public Func<object, T1, T2, T3, T4, T5, TResult> BuildFunc<T1, T2, T3, T4, T5, TResult>(MethodInfo method)
         {
             var func = (Func<object, T1, T2, T3, T4, T5, TResult>) _cache.GetValueOrDefault(method);
-            if (func != null) return func;
+            if (func is object) return func;
             func = _builder.BuildFunc<T1, T2, T3, T4, T5, TResult>(method);
             _cache.AddOrUpdate(method, func);
             return func;
diff --git a/src/Weakly/Builders/CachingPropertyAccessorBuilderDecorator.cs b/src/Weakly/Builders/CachingPropertyAccessorBuilderDecorator.cs
index f108d54..e4b4717 100644
--- a/src/Weakly/Builders/CachingPropertyAccessorBuilderDecorator.cs
+++ b/src/Weakly/Builders/CachingPropertyAccessorBuilderDecorator.cs
@@ -31,7 +31,7 @@ public CachingPropertyAccessorBuilderDecorator(IPropertyAccessorBuilder builder)
         public Func<object, object> BuildGetter(PropertyInfo property)
         {
             var action = _getterCache.GetValueOrDefault(property);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildGetter(property);
             _getterCache.AddOrUpdate(property, action);
             return action;
@@ -47,7 +47,7 @@ public Func<object, object> BuildGetter(PropertyInfo property)
         public Action<object, object> BuildSetter(PropertyInfo property)
         {
             var action = _setterCache.GetValueOrDefault(property);
-            if (action != null) return action;
+            if (action is object) return action;
             action = _builder.BuildSetter(property);
             _setterCache.AddOrUpdate(property, action);
             return action;
diff --git a/src/Weakly/Builders/SimpleCache.cs b/src/Weakly/Builders/SimpleCache.cs
index 60d5afd..4d026e1 100644
--- a/src/Weakly/Builders/SimpleCache.cs
+++ b/src/Weakly/Builders/SimpleCache.cs
@@ -4,12 +4,7 @@ namespace Weakly.Builders
 {
     internal sealed class SimpleCache<TKey, TValue>
     {
-        private readonly IDictionary<TKey, TValue> _storage;
-
-        public SimpleCache()
-        {
-            _storage = new Dictionary<TKey, TValue>();
-        }
+        private readonly Dictionary<TKey, TValue> _storage = new Dictionary<TKey, TValue>();
 
         public TValue GetValueOrDefault(TKey key)
         {
diff --git a/src/Weakly/Collections/WeakCollection.cs b/src/Weakly/Collections/WeakCollection.cs
index 39250ff..4977d4e 100644
--- a/src/Weakly/Collections/WeakCollection.cs
+++ b/src/Weakly/Collections/WeakCollection.cs
@@ -72,7 +72,7 @@ public IEnumerator<T> GetEnumerator()
             CleanIfNeeded();
 
             var enumerable = _inner.Select(item => (T) item.Target)
-                .Where(value => value != null);
+                .Where(value => value is object);
             return enumerable.GetEnumerator();
         }
 
@@ -119,7 +119,7 @@ public void CopyTo(T[] array, int arrayIndex)
         {
             CleanIfNeeded();
 
-            if (array == null)
+            if (array is null)
                 throw new ArgumentNullException(nameof(array));
             if (arrayIndex < 0 || arrayIndex >= array.Length)
                 throw new ArgumentOutOfRangeException(nameof(arrayIndex));
@@ -127,7 +127,7 @@ public void CopyTo(T[] array, int arrayIndex)
                 throw new ArgumentException("The number of elements in the source collection is greater than the available space from arrayIndex to the end of the destination array.");
 
             var items = _inner.Select(item => (T) item.Target)
-                .Where(value => value != null)
+                .Where(value => value is object)
                 .ToArray();
 
             items.CopyTo(array, arrayIndex);
diff --git a/src/Weakly/Collections/WeakValueDictionary.cs b/src/Weakly/Collections/WeakValueDictionary.cs
index 77646f8..a02924e 100644
--- a/src/Weakly/Collections/WeakValueDictionary.cs
+++ b/src/Weakly/Collections/WeakValueDictionary.cs
@@ -121,7 +121,7 @@ public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
             CleanIfNeeded();
 
             var enumerable = _inner.Select(pair => new KeyValuePair<TKey, TValue>(pair.Key, (TValue) pair.Value.Target))
-                .Where(pair => pair.Value != null);
+                .Where(pair => pair.Value is object);
             return enumerable.GetEnumerator();
         }
 
@@ -156,7 +156,7 @@ void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[]
         {
             CleanIfNeeded();
 
-            if (array == null)
+            if (array is null)
                 throw new ArgumentNullException(nameof(array));
             if (arrayIndex < 0 || arrayIndex >= array.Length)
                 throw new ArgumentOutOfRangeException(nameof(arrayIndex));
@@ -164,7 +164,7 @@ void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[]
                 throw new ArgumentException("The number of elements in the source collection is greater than the available space from arrayIndex to the end of the destination array.");
 
             var items = _inner.Select(pair => new KeyValuePair<TKey, TValue>(pair.Key, (TValue) pair.Value.Target))
-                .Where(pair => pair.Value != null)
+                .Where(pair => pair.Value is object)
                 .ToArray();
 
             items.CopyTo(array, arrayIndex);
@@ -256,7 +256,7 @@ public bool TryGetValue(TKey key, out TValue value)
             }
 
             value = (TValue) wr.Target;
-            if (value == null)
+            if (value is null)
             {
                 _inner.Remove(key);
                 return false;
@@ -343,7 +343,7 @@ bool ICollection<TValue>.Contains(TValue item)
 
             public void CopyTo(TValue[] array, int arrayIndex)
             {
-                if (array == null)
+                if (array is null)
                     throw new ArgumentNullException(nameof(array));
                 if (arrayIndex < 0 || arrayIndex >= array.Length)
                     throw new ArgumentOutOfRangeException(nameof(arrayIndex));
diff --git a/src/Weakly/Delegates/DisposableAction.cs b/src/Weakly/Delegates/DisposableAction.cs
index 734ed7e..12efaeb 100644
--- a/src/Weakly/Delegates/DisposableAction.cs
+++ b/src/Weakly/Delegates/DisposableAction.cs
@@ -15,7 +15,7 @@ public sealed class DisposableAction : IDisposable
         /// <param name="action">The action to execute on dispose.</param>
         public DisposableAction(Action action)
         {
-            if (action == null)
+            if (action is null)
                 throw new ArgumentNullException(nameof(action));
 
             _action = action;
@@ -26,7 +26,7 @@ public DisposableAction(Action action)
         /// </summary>
         public void Dispose()
         {
-            if (_action == null) return;
+            if (_action is null) return;
             _action();
             _action = null;
         }
diff --git a/src/Weakly/Delegates/WeakAction.cs b/src/Weakly/Delegates/WeakAction.cs
index 86e093a..ea99a14 100644
--- a/src/Weakly/Delegates/WeakAction.cs
+++ b/src/Weakly/Delegates/WeakAction.cs
@@ -19,9 +19,9 @@ public sealed class WeakAction<TTarget>
         /// <param name="weakAction">The method represented by the delegate.</param>
         public WeakAction(TTarget target, [EmptyCapture] Action<TTarget> weakAction)
         {
-            if (target == null)
+            if (target is null)
                 throw new ArgumentNullException(nameof(target));
-            if (weakAction == null)
+            if (weakAction is null)
                 throw new ArgumentNullException(nameof(weakAction));
 
             _target = new WeakReference<TTarget>(target);
diff --git a/src/Weakly/Delegates/WeakFunc.cs b/src/Weakly/Delegates/WeakFunc.cs
index 4b9282d..eab8d8b 100644
--- a/src/Weakly/Delegates/WeakFunc.cs
+++ b/src/Weakly/Delegates/WeakFunc.cs
@@ -20,9 +20,9 @@ public sealed class WeakFunc<TTarget, TResult>
         /// <param name="weakFunc">The method represented by the delegate.</param>
         public WeakFunc(TTarget target, [EmptyCapture] Func<TTarget, TResult> weakFunc)
         {
-            if (target == null)
+            if (target is null)
                 throw new ArgumentNullException(nameof(target));
-            if (weakFunc == null)
+            if (weakFunc is null)
                 throw new ArgumentNullException(nameof(weakFunc));
 
             _target = new WeakReference<TTarget>(target);
diff --git a/src/Weakly/Events/WeakEventHandler.cs b/src/Weakly/Events/WeakEventHandler.cs
index dc05685..2b41d4f 100644
--- a/src/Weakly/Events/WeakEventHandler.cs
+++ b/src/Weakly/Events/WeakEventHandler.cs
@@ -20,7 +20,7 @@ public static class WeakEventHandler
         /// <param name="weakHandler">The weak handler.</param>
         /// <returns>A registration object that can be used to deregister from the event.</returns>
         public static IDisposable RegisterPropertyChangingWeak<TSubscriber>(this INotifyPropertyChanging source,
-            TSubscriber subscriber, Action<TSubscriber, object, PropertyChangingEventArgs> weakHandler)
+            TSubscriber subscriber, [EmptyCapture] Action<TSubscriber, object, PropertyChangingEventArgs> weakHandler)
             where TSubscriber : class
         {
             return new WeakNotifyPropertyChangingHandler<TSubscriber>(source, subscriber, weakHandler);
diff --git a/src/Weakly/IO/MemoryTributary.cs b/src/Weakly/IO/MemoryTributary.cs
index 75a307f..ef73f58 100644
--- a/src/Weakly/IO/MemoryTributary.cs
+++ b/src/Weakly/IO/MemoryTributary.cs
@@ -145,7 +145,7 @@ public override int Read(byte[] buffer, int offset, int count)
             if (lcount > remaining)
                 lcount = remaining;
 
-            if (buffer == null)
+            if (buffer is null)
             {
                 throw new ArgumentNullException(nameof(buffer), "Buffer cannot be null.");
             }
diff --git a/src/Weakly/Reflection/ReflectionPath.cs b/src/Weakly/Reflection/ReflectionPath.cs
index 6884538..caed8be 100644
--- a/src/Weakly/Reflection/ReflectionPath.cs
+++ b/src/Weakly/Reflection/ReflectionPath.cs
@@ -19,7 +19,7 @@ public sealed class ReflectionPath
         /// <param name="path">The reflection path.</param>
         public ReflectionPath(string path)
         {
-            if (path == null)
+            if (path is null)
                 throw new ArgumentNullException(nameof(path));
 
             _items = path.Split('.');
@@ -34,13 +34,13 @@ public ReflectionPath(string path)
         /// <returns>The value.</returns>
         public object GetValue(object source)
         {
-            if (source == null)
+            if (source is null)
                 throw new ArgumentNullException(nameof(source));
 
             var current = source;
             for (var i = 0; i < _items.Length; i++)
             {
-                if (current == null)
+                if (current is null)
                     throw new NullReferenceException(
                         string.Format(
                             "Could not get the value of the property path '{0}' because '{1}' is null on object '{2}'.",
@@ -52,10 +52,10 @@ public object GetValue(object source)
 
                 var getValue = _getters[i];
                 var currentType = current.GetType();
-                if (getValue == null || _reflectedTypes[i] != currentType)
+                if (getValue is null || _reflectedTypes[i] != currentType)
                 {
                     var pi = currentType.GetRuntimeProperty(_items[i]);
-                    if (pi == null)
+                    if (pi is null)
                         throw new InvalidOperationException(
                             string.Format(
                                 "Could not find property '{0}' on type '{1}'.",
diff --git a/src/Weakly/Tasks/ApmHelper.cs b/src/Weakly/Tasks/ApmHelper.cs
index 78b4d05..f6cd66f 100644
--- a/src/Weakly/Tasks/ApmHelper.cs
+++ b/src/Weakly/Tasks/ApmHelper.cs
@@ -18,12 +18,12 @@ public static class ApmHelper
         /// <returns>The asynchronous operation, to be returned by the Begin method of the APM pattern.</returns>
         public static IAsyncResult ToBegin<TResult>(this Task<TResult> task, AsyncCallback callback, object state)
         {
-            if (task == null)
+            if (task is null)
                 throw new ArgumentNullException(nameof(task));
 
             if (task.AsyncState == state)
             {
-                if (callback != null)
+                if (callback is object)
                 {
                     task.ContinueWith(
                         (t, cb) => ((AsyncCallback)cb)(t),
@@ -53,7 +53,7 @@ public static IAsyncResult ToBegin<TResult>(this Task<TResult> task, AsyncCallba
                         tcs.TrySetResult(t.Result);
                     }
 
-                    if (callback != null)
+                    if (callback is object)
                     {
                         callback(tcs.Task);
                     }
@@ -74,12 +74,12 @@ public static IAsyncResult ToBegin<TResult>(this Task<TResult> task, AsyncCallba
         /// <returns>The asynchronous operation, to be returned by the Begin method of the APM pattern.</returns>
         public static IAsyncResult ToBegin(this Task task, AsyncCallback callback, object state)
         {
-            if (task == null)
+            if (task is null)
                 throw new ArgumentNullException(nameof(task));
 
             if (task.AsyncState == state)
             {
-                if (callback != null)
+                if (callback is object)
                 {
                     task.ContinueWith(
                         (t, cb) => ((AsyncCallback)cb)(t),
@@ -109,7 +109,7 @@ public static IAsyncResult ToBegin(this Task task, AsyncCallback callback, objec
                         tcs.TrySetResult(null);
                     }
 
-                    if (callback != null)
+                    if (callback is object)
                     {
                         callback(tcs.Task);
                     }
diff --git a/src/Weakly/Tasks/TaskEventArgs.cs b/src/Weakly/Tasks/TaskEventArgs.cs
index 797237a..8999fed 100644
--- a/src/Weakly/Tasks/TaskEventArgs.cs
+++ b/src/Weakly/Tasks/TaskEventArgs.cs
@@ -16,7 +16,7 @@ public sealed class TaskEventArgs : EventArgs
         /// <param name="task">The supplied Task.</param>
         public TaskEventArgs(Task task)
         {
-            if (task == null)
+            if (task is null)
                 throw new ArgumentNullException(nameof(task));
 
             _task = task;
diff --git a/src/Weakly/Tasks/TaskHelper.cs b/src/Weakly/Tasks/TaskHelper.cs
index a7a0935..a7b5de0 100644
--- a/src/Weakly/Tasks/TaskHelper.cs
+++ b/src/Weakly/Tasks/TaskHelper.cs
@@ -137,7 +137,7 @@ public static Task<T> FailFastOnException<T>(this Task<T> task)
         private static void OnTaskFaulted(Task task)
         {
             var handler = TaskFaulted;
-            if (handler != null)
+            if (handler is object)
                 handler(null, new TaskEventArgs(task));
         }
 
@@ -208,11 +208,11 @@ public static void PropagateExceptionsTo(this Task task, SynchronizationContext
         /// <param name="task">The task to watch.</param>
         public static void Watch(this Task task)
         {
-            if (task == null)
+            if (task is null)
                 throw new ArgumentNullException(nameof(task));
 
             var handler = TaskWatched;
-            if (handler != null)
+            if (handler is object)
                 handler(null, new TaskEventArgs(task));
         }