diff --git a/tests/Avalonia.Layout.UnitTests/Properties/AssemblyInfo.cs b/tests/Avalonia.Layout.UnitTests/Properties/AssemblyInfo.cs
index 5db24ea6e5..a4f0c4c341 100644
--- a/tests/Avalonia.Layout.UnitTests/Properties/AssemblyInfo.cs
+++ b/tests/Avalonia.Layout.UnitTests/Properties/AssemblyInfo.cs
@@ -4,3 +4,6 @@
 using System.Reflection;
 
 [assembly: AssemblyTitle("Avalonia.Layout.UnitTests")]
+
+// Don't run tests in parallel.
+[assembly: CollectionBehavior(DisableTestParallelization = true)]
\ No newline at end of file