diff --git a/tests/Avalonia.Markup.UnitTests/Parsers/ExpressionObserverBuilderTests_AttachedProperty.cs b/tests/Avalonia.Markup.UnitTests/Parsers/ExpressionObserverBuilderTests_AttachedProperty.cs
index 7c48a975ef..e5e63b24d0 100644
--- a/tests/Avalonia.Markup.UnitTests/Parsers/ExpressionObserverBuilderTests_AttachedProperty.cs
+++ b/tests/Avalonia.Markup.UnitTests/Parsers/ExpressionObserverBuilderTests_AttachedProperty.cs
@@ -117,9 +117,11 @@ namespace Avalonia.Markup.UnitTests.Parsers
             var result = run();
             result.Item1.Subscribe(x => { });
 
-            GC.Collect();
+            // Mono trickery
+            GC.Collect(2);
             GC.WaitForPendingFinalizers();
-            GC.Collect();
+            GC.WaitForPendingFinalizers();
+            GC.Collect(2);
 
             Assert.Null(result.Item2.Target);
         }