diff --git a/test/PowerShellEditorServices.Test/Extensions/ExtensionCommandTests.cs b/test/PowerShellEditorServices.Test/Extensions/ExtensionCommandTests.cs
index 70e35d3dd..11d7f61cd 100644
--- a/test/PowerShellEditorServices.Test/Extensions/ExtensionCommandTests.cs
+++ b/test/PowerShellEditorServices.Test/Extensions/ExtensionCommandTests.cs
@@ -93,12 +93,14 @@ public async Task CanRegisterAndInvokeCommandWithScriptBlock()
             const string commandName = "test.scriptblock";
             const string commandDisplayName = "ScriptBlock extension";
 
+            // Use AddScript so the script block is created in PowerShell's own session state
+            // rather than C#'s module context. ScriptBlock.Create() binds to the C# module,
+            // so $global: writes made via Invoke-Command land in an isolated scope on PS 5.1.
             await psesHost.ExecutePSCommandAsync(
                 new PSCommand()
-                    .AddCommand("Register-EditorCommand")
-                    .AddParameter("Name", commandName)
-                    .AddParameter("DisplayName", commandDisplayName)
-                    .AddParameter("ScriptBlock", ScriptBlock.Create("$global:extensionValue = 10")),
+                    .AddScript(
+                        $"Register-EditorCommand -Name '{commandName}' -DisplayName \"{commandDisplayName}\" " +
+                        "-ScriptBlock { $global:extensionValue = 10 }"),
                 CancellationToken.None);
 
             Assert.NotNull(commandAdded);
@@ -106,10 +108,9 @@ await psesHost.ExecutePSCommandAsync(
             Assert.Equal(commandDisplayName, commandAdded.DisplayName);
 
             // Invoke the command.
-            // TODO: What task was this cancelling?
-            await extensionCommandService.InvokeCommandAsync("test.scriptblock", editorContext);
+            await extensionCommandService.InvokeCommandAsync(commandName, editorContext);
 
-            // Assert the expected value
+            // Assert the expected value.
             PSCommand psCommand = new PSCommand().AddScript("$global:extensionValue");
             IEnumerable<int> results = await psesHost.ExecutePSCommandAsync<int>(psCommand, CancellationToken.None);
             Assert.Equal(10, results.FirstOrDefault());