diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Properties/AssemblyInfo.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Properties/AssemblyInfo.cs
index 034e9f74ce..a8034f484a 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Properties/AssemblyInfo.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Properties/AssemblyInfo.cs
@@ -7,4 +7,5 @@ using Xunit;
 [assembly: AssemblyTitle("Avalonia.Markup.Xaml.UnitTests")]
 
 // Don't run tests in parallel.
-[assembly: CollectionBehavior(DisableTestParallelization = true)]
\ No newline at end of file
+[assembly: CollectionBehavior(DisableTestParallelization = true)]
+[assembly: CollectionBehavior(MaxParallelThreads = 1)]