diff --git a/src/Prism.Avalonia/Common/AnonymousObserver.cs b/src/Prism.Avalonia/Common/AnonymousObserver.cs
deleted file mode 100644
index c541590..0000000
--- a/src/Prism.Avalonia/Common/AnonymousObserver.cs
+++ /dev/null
@@ -1,67 +0,0 @@
-using System;
-using System.Threading.Tasks;
-
-namespace Prism.Common
-{
-    /// <summary>
-    /// Class to create an <see cref="IObserver{T}"/> instance from delegate-based implementations of the On* methods.
-    /// </summary>
-    /// <typeparam name="T">The type of the elements in the sequence.</typeparam>
-    public class AnonymousObserver<T> : IObserver<T>
-    {
-        private static readonly Action<Exception> ThrowsOnError = ex => throw ex;
-        private static readonly Action NoOpCompleted = () => { };
-        private readonly Action<T> _onNext;
-        private readonly Action<Exception> _onError;
-        private readonly Action _onCompleted;
-
-        public AnonymousObserver(TaskCompletionSource<T> tcs)
-        {
-            if (tcs is null)
-            {
-                throw new ArgumentNullException(nameof(tcs));
-            }
-
-            _onNext = tcs.SetResult;
-            _onError = tcs.SetException;
-            _onCompleted = NoOpCompleted;
-        }
-
-        public AnonymousObserver(Action<T> onNext, Action<Exception> onError, Action onCompleted)
-        {
-            _onNext = onNext ?? throw new ArgumentNullException(nameof(onNext));
-            _onError = onError ?? throw new ArgumentNullException(nameof(onError));
-            _onCompleted = onCompleted ?? throw new ArgumentNullException(nameof(onCompleted));
-        }
-
-        public AnonymousObserver(Action<T> onNext)
-            : this(onNext, ThrowsOnError, NoOpCompleted)
-        {
-        }
-
-        public AnonymousObserver(Action<T> onNext, Action<Exception> onError)
-            : this(onNext, onError, NoOpCompleted)
-        {
-        }
-
-        public AnonymousObserver(Action<T> onNext, Action onCompleted)
-            : this(onNext, ThrowsOnError, onCompleted)
-        {
-        }
-
-        public void OnCompleted()
-        {
-            _onCompleted.Invoke();
-        }
-
-        public void OnError(Exception error)
-        {
-            _onError.Invoke(error);
-        }
-
-        public void OnNext(T value)
-        {
-            _onNext.Invoke(value);
-        }
-    }
-}
diff --git a/src/Prism.Avalonia/Extensions/ObservableExtensions.cs b/src/Prism.Avalonia/Extensions/ObservableExtensions.cs
index fef1d97..dad8f94 100644
--- a/src/Prism.Avalonia/Extensions/ObservableExtensions.cs
+++ b/src/Prism.Avalonia/Extensions/ObservableExtensions.cs
@@ -1,9 +1,10 @@
 using System;
+using Avalonia.Reactive;
 using Prism.Common;
 
 namespace Prism.Extensions
 {
-    public static class ObservableExtensions
+    internal static class ObservableExtensions
     {
         /// <summary>
         /// Subscribes an element handler to an observable sequence.
diff --git a/src/Prism.Avalonia/Properties/AssemblyInfo.cs b/src/Prism.Avalonia/Properties/AssemblyInfo.cs
index e503e22..3cfc4be 100644
--- a/src/Prism.Avalonia/Properties/AssemblyInfo.cs
+++ b/src/Prism.Avalonia/Properties/AssemblyInfo.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Avalonia.Metadata;
 
@@ -18,3 +19,5 @@
 [assembly: XmlnsDefinition("http://prismlibrary.com/", "Prism.Interactivity")]
 [assembly: XmlnsDefinition("http://prismlibrary.com/", "Prism.Services.Dialogs")]
 [assembly: XmlnsDefinition("http://prismlibrary.com/", "Prism.Ioc")]
+
+[assembly: InternalsVisibleTo("Prism.Avalonia.Tests")]