diff --git a/LightweightIocContainer/IocContainer.cs b/LightweightIocContainer/IocContainer.cs
index 7ecba5c..b820f3b 100644
--- a/LightweightIocContainer/IocContainer.cs
+++ b/LightweightIocContainer/IocContainer.cs
@@ -6,6 +6,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using JetBrains.Annotations;
 using LightweightIocContainer.Exceptions;
 using LightweightIocContainer.Interfaces;
 using LightweightIocContainer.Interfaces.Registrations;
@@ -201,6 +202,7 @@ namespace LightweightIocContainer
         /// <param name="type">The type that will be created</param>
         /// <param name="arguments">The existing arguments</param>
         /// <returns>An array of all needed constructor arguments to create <param name="type"></param></returns>
+        [CanBeNull]
         private object[] ResolveConstructorArguments(Type type, object[] arguments)
         {
             //find best ctor
diff --git a/LightweightIocContainer/LightweightIocContainer.csproj b/LightweightIocContainer/LightweightIocContainer.csproj
index 5d2b1a3..a305561 100644
--- a/LightweightIocContainer/LightweightIocContainer.csproj
+++ b/LightweightIocContainer/LightweightIocContainer.csproj
@@ -17,6 +17,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="JetBrains.Annotations" Version="2019.1.1" />
     <PackageReference Include="System.Reflection.Emit" Version="4.3.0" />
   </ItemGroup>
 
diff --git a/Test.LightweightIocContainer/IocContainerTest.cs b/Test.LightweightIocContainer/IocContainerTest.cs
index 480d09b..7d597d7 100644
--- a/Test.LightweightIocContainer/IocContainerTest.cs
+++ b/Test.LightweightIocContainer/IocContainerTest.cs
@@ -1,3 +1,4 @@
+using JetBrains.Annotations;
 using LightweightIocContainer;
 using LightweightIocContainer.Exceptions;
 using LightweightIocContainer.Interfaces;
@@ -18,6 +19,7 @@ namespace Test.LightweightIocContainer
 
         }
 
+        [UsedImplicitly]
         public interface ITestFactory
         {
             ITest Create();
@@ -35,6 +37,7 @@ namespace Test.LightweightIocContainer
 
         }
 
+        [UsedImplicitly]
         private class TestConstructor : ITest
         {
             public TestConstructor(string name, Test test)
@@ -87,7 +90,7 @@ namespace Test.LightweightIocContainer
             IIocContainer iocContainer = new IocContainer();
 
             iocContainer.Register(RegistrationFactory.Register<ITest, Test>());
-            var exception = Assert.Throws<MultipleRegistrationException>(() => iocContainer.Register(RegistrationFactory.Register<ITest, TestConstructor>()));
+            MultipleRegistrationException exception = Assert.Throws<MultipleRegistrationException>(() => iocContainer.Register(RegistrationFactory.Register<ITest, TestConstructor>()));
             Assert.AreEqual(typeof(ITest), exception.Type);
         }
 
@@ -104,7 +107,7 @@ namespace Test.LightweightIocContainer
         {
             IIocContainer iocContainer = new IocContainer();
 
-            var exception = Assert.Throws<TypeNotRegisteredException>(() => iocContainer.Resolve<ITest>());
+            TypeNotRegisteredException exception = Assert.Throws<TypeNotRegisteredException>(() => iocContainer.Resolve<ITest>());
             Assert.AreEqual(typeof(ITest), exception.Type);
         }
 
@@ -189,7 +192,7 @@ namespace Test.LightweightIocContainer
             IIocContainer iocContainer = new IocContainer();
             iocContainer.Register(RegistrationFactory.Register<ITest, Test, MultitonScope>());
 
-            var exception = Assert.Throws<MultitonResolveException>(() => iocContainer.Resolve<ITest>());
+            MultitonResolveException exception = Assert.Throws<MultitonResolveException>(() => iocContainer.Resolve<ITest>());
             Assert.AreEqual(typeof(ITest), exception.Type);
         }
 
@@ -199,7 +202,7 @@ namespace Test.LightweightIocContainer
             IIocContainer iocContainer = new IocContainer();
             iocContainer.Register(RegistrationFactory.Register<ITest, Test, MultitonScope>());
 
-            var exception = Assert.Throws<MultitonResolveException>(() => iocContainer.Resolve<ITest>(new object()));
+            MultitonResolveException exception = Assert.Throws<MultitonResolveException>(() => iocContainer.Resolve<ITest>(new object()));
             Assert.AreEqual(typeof(ITest), exception.Type);
         }
 
diff --git a/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj b/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj
index ee759da..5fa4de4 100644
--- a/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj
+++ b/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj
@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="JetBrains.Annotations" Version="2019.1.1" />
     <PackageReference Include="Moq" Version="4.11.0" />
     <PackageReference Include="nunit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.13.0" />