diff --git a/src/Serializers/SerializerResolver.cs b/src/Serializers/SerializerResolver.cs
index 1ee45d9..a4dfa8f 100644
--- a/src/Serializers/SerializerResolver.cs
+++ b/src/Serializers/SerializerResolver.cs
@@ -51,6 +51,11 @@ public static void Register<T, TSerializer>(DataDirection direction = DataDirect
         /// <typeparam name="TSerializer">The serializer to apply</typeparam>
         public static void Register<TSerializer>(Type targetType, DataDirection direction = DataDirection.All) where TSerializer : ApiSerializer, new()
         {
+            if (!targetType.IsClass)
+            {
+                throw new ArgumentException($"{targetType.Name} is not a class", nameof(targetType));
+            }
+
             if (direction.HasFlag(DataDirection.In))
             {
                 DeserializerMap[targetType] = typeof(TSerializer);
@@ -79,7 +84,7 @@ public static void Unregister<T>(DataDirection direction = DataDirection.All) wh
         /// <param name="direction">Whether this serializer should be removed from incoming/outgoing data</param>
         public static void Unregister(Type targetType, DataDirection direction = DataDirection.All)
         {
-            if (targetType.IsClass)
+            if (!targetType.IsClass)
             {
                 throw new ArgumentException($"{targetType.Name} is not a class", nameof(targetType));
             }
diff --git a/tests/Serializers/SerializerResolverTests.cs b/tests/Serializers/SerializerResolverTests.cs
index 41bf02c..0323af8 100644
--- a/tests/Serializers/SerializerResolverTests.cs
+++ b/tests/Serializers/SerializerResolverTests.cs
@@ -20,6 +20,8 @@ public void Setup()
 
             // anothertestobject will use the dummyserializer
             SerializerResolver.Register<AnotherTestObject, DummySerializer>();
+
+            SerializerResolver.Register<DummySerializer>(typeof(TestContainer<>));
         }
 
         [Test]
@@ -27,6 +29,8 @@ public void TestResolution()
         {
             Assert.AreEqual(typeof(ApiXmlSerializer), Client.Serializer.Resolve<TestObject>(DataDirection.In).GetType());
             Assert.AreEqual(typeof(ApiJsonSerializer), Client.Serializer.Resolve<YetAnotherTestObject>(DataDirection.Out).GetType());
+
+            Assert.AreEqual(typeof(DummySerializer), Client.Serializer.Resolve<TestContainer<TestObject>>(DataDirection.In).GetType());
         }
 
         [Test]
@@ -66,6 +70,11 @@ public class YetAnotherTestObject
     {
     }
 
+    public class TestContainer<T>
+    {
+        public T Item { get; set; }
+    }
+
     public class DummySerializer : ApiSerializer
     {
         public override string ContentType => "nothing";