--- a/layout/tools/reftest/manifest.jsm
+++ b/layout/tools/reftest/manifest.jsm
@@ -556,17 +556,17 @@ sandbox.compareRetainedDisplayLists = g.
     sandbox.stylo = styloEnabled && !g.compareStyloToGecko;
     sandbox.styloVsGecko = g.compareStyloToGecko;
 #else
     sandbox.stylo = false;
     sandbox.styloVsGecko = false;
 #endif
 
 // Printing via Skia PDF is only supported on Mac for now.
-#ifdef XP_MACOSX && MOZ_ENABLE_SKIA_PDF
+#if defined(XP_MACOSX) && defined(MOZ_ENABLE_SKIA_PDF)
     sandbox.skiaPdf = true;
 #else
     sandbox.skiaPdf = false;
 #endif
 
 #ifdef RELEASE_OR_BETA
     sandbox.release_or_beta = true;
 #else