diff --git a/layout/tools/layout-debug/src/moz.build b/layout/tools/layout-debug/src/moz.build
index be7abcab0f..b3f7d5e062 100644
--- a/layout/tools/layout-debug/src/moz.build
+++ b/layout/tools/layout-debug/src/moz.build
@@ -15,7 +15,7 @@ EXPORTS += [
     'nsLayoutDebugCIID.h',
 ]
 
-UNIFIED_SOURCES += [
+SOURCES += [
     'nsDebugFactory.cpp',
     'nsLayoutDebugCLH.cpp',
     'nsLayoutDebuggingTools.cpp',