diff --git a/dev/dll/Microsoft.UI.Xaml.vcxproj b/dev/dll/Microsoft.UI.Xaml.vcxproj
index a392a17e42..97c1ceb897 100644
--- a/dev/dll/Microsoft.UI.Xaml.vcxproj
+++ b/dev/dll/Microsoft.UI.Xaml.vcxproj
@@ -250,7 +250,7 @@
       <Optimization Condition="'$(Configuration)'=='Release'">MinSpace</Optimization>
       <ConformanceMode>true</ConformanceMode>
       <!-- Disable multi-proc building on low powered machines, such as the lab machines -->
-      <MultiProcessorCompilation Condition="'$(NUMBER_OF_PROCESSORS)'=='2'">false</MultiProcessorCompilation>
+      <MultiProcessorCompilation Condition="'$(TF_BUILD)'=='True'">false</MultiProcessorCompilation>
     </ClCompile>
   </ItemDefinitionGroup>
   <ItemGroup>