diff --git a/Pilz.Plugins.Advanced/PluginFeatureController.cs b/Pilz.Plugins.Advanced/PluginFeatureController.cs
index 4650536..d63d08f 100644
--- a/Pilz.Plugins.Advanced/PluginFeatureController.cs
+++ b/Pilz.Plugins.Advanced/PluginFeatureController.cs
@@ -111,7 +111,7 @@ public class PluginFeatureController
     /// <param name="namespace">If not null, the type will only be processed if it's within the given namespace.</param>
     public void RegisterAll(Type type, string? @namespace = null)
     {
-        if (@namespace != null && type.Namespace != null && type.Namespace != @namespace && !type.Namespace.StartsWith(@namespace + "."))
+        if (@namespace != null && type.Namespace != null && type.Namespace != @namespace && !type.Namespace.StartsWith(@namespace + ".") || type.IsAbstract)
             return;
 
         if (type.IsAssignableTo(typeof(IPluginFeaturesProvider)))
@@ -171,11 +171,8 @@ public class PluginFeatureController
     /// <param name="module"></param>
     public void Register(PluginFeature module)
     {
-        if (!features.Contains(module))
-        {
-            features.Add(module);
+        if (features.Add(module))
             OnPluginFeatureReistred?.Invoke(this, module);
-        }
     }
 
     /// <summary>