diff --git a/tests/Avalonia.LeakTests/app.config b/tests/Avalonia.LeakTests/app.config
index 71e6d0a02e..d012dee914 100644
--- a/tests/Avalonia.LeakTests/app.config
+++ b/tests/Avalonia.LeakTests/app.config
@@ -12,4 +12,10 @@
       </dependentAssembly>
     </assemblyBinding>
   </runtime>
-<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7"/></startup></configuration>
+  <startup>
+    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7"/>
+  </startup>
+  <system.diagnostics>
+    <assert assertuienabled="false"/>
+  </system.diagnostics>
+</configuration>