diff --git a/src/core/Akka.TestKit.Tests/TestFSMRefTests!/TestFSMRefSpec.cs b/src/core/Akka.TestKit.Tests/TestFSMRefTests/TestFSMRefSpec.cs
similarity index 58%
rename from src/core/Akka.TestKit.Tests/TestFSMRefTests!/TestFSMRefSpec.cs
rename to src/core/Akka.TestKit.Tests/TestFSMRefTests/TestFSMRefSpec.cs
index 1cda19f477e..54565dfdb30 100644
--- a/src/core/Akka.TestKit.Tests/TestFSMRefTests!/TestFSMRefSpec.cs
+++ b/src/core/Akka.TestKit.Tests/TestFSMRefTests/TestFSMRefSpec.cs
@@ -5,50 +5,51 @@
 // </copyright>
 //-----------------------------------------------------------------------
 
-using System;
+using System.Threading.Tasks;
 using Akka.Actor;
-using Akka.TestKit;
 using Xunit;
+using FluentAssertions;
+using FluentAssertions.Extensions;
 
-namespace Akka.Testkit.Tests.TestFSMRefTests
+namespace Akka.TestKit.Tests.TestFSMRefTests
 {
     public class TestFSMRefSpec : AkkaSpec
     {
         [Fact]
-        public void A_TestFSMRef_must_allow_access_to_internal_state()
+        public async Task A_TestFSMRef_must_allow_access_to_internal_state()
         {
             var fsm = ActorOfAsTestFSMRef<StateTestFsm, int, string>("test-fsm-ref-1");
 
-            fsm.StateName.ShouldBe(1);
-            fsm.StateData.ShouldBe("");
+            fsm.StateName.Should().Be(1);
+            fsm.StateData.Should().Be("");
 
             fsm.Tell("go");
-            fsm.StateName.ShouldBe(2);
-            fsm.StateData.ShouldBe("go");
+            fsm.StateName.Should().Be(2);
+            fsm.StateData.Should().Be("go");
 
             fsm.SetState(1);
-            fsm.StateName.ShouldBe(1);
-            fsm.StateData.ShouldBe("go");
+            fsm.StateName.Should().Be(1);
+            fsm.StateData.Should().Be("go");
 
             fsm.SetStateData("buh");
-            fsm.StateName.ShouldBe(1);
-            fsm.StateData.ShouldBe("buh");
+            fsm.StateName.Should().Be(1);
+            fsm.StateData.Should().Be("buh");
 
-            fsm.SetStateTimeout(TimeSpan.FromMilliseconds(100));
-            Within(TimeSpan.FromMilliseconds(80), TimeSpan.FromMilliseconds(500), () =>
-                AwaitCondition(() => fsm.StateName == 2 && fsm.StateData == "timeout")
-                );
+            fsm.SetStateTimeout(100.Milliseconds());
+            await WithinAsync(80.Milliseconds(), 500.Milliseconds(), async () =>
+                await AwaitConditionAsync(() => fsm.StateName == 2 && fsm.StateData == "timeout")
+            );
         }
 
         [Fact]
         public void A_TestFSMRef_must_allow_access_to_timers()
         {
             var fsm = ActorOfAsTestFSMRef<TimerTestFsm, int, object>("test-fsm-ref-2");
-            fsm.IsTimerActive("test").ShouldBe(false);
-            fsm.SetTimer("test", 12, TimeSpan.FromMilliseconds(10), true);
-            fsm.IsTimerActive("test").ShouldBe(true);
+            fsm.IsTimerActive("test").Should().Be(false);
+            fsm.SetTimer("test", 12, 10.Milliseconds(), true);
+            fsm.IsTimerActive("test").Should().Be(true);
             fsm.CancelTimer("test");
-            fsm.IsTimerActive("test").ShouldBe(false);
+            fsm.IsTimerActive("test").Should().Be(false);
         }
 
         private class StateTestFsm : FSM<int, string>
@@ -56,20 +57,22 @@ private class StateTestFsm : FSM<int, string>
             public StateTestFsm()
             {
                 StartWith(1, "");
+                
                 When(1, e =>
                 {
                     var fsmEvent = e.FsmEvent;
                     if(Equals(fsmEvent, "go"))
-                        return GoTo(2, "go");
+                        return GoTo(2).Using("go");
                     if(fsmEvent is StateTimeout)
-                        return GoTo(2, "timeout");
+                        return GoTo(2).Using("timeout");
                     return null;
                 });
+                
                 When(2, e =>
                 {
                     var fsmEvent = e.FsmEvent;
                     if(Equals(fsmEvent, "back"))
-                        return GoTo(1, "back");
+                        return GoTo(1).Using("back");
                     return null;
                 });
             }