diff --git a/toolkit/components/startup/moz.build b/toolkit/components/startup/moz.build
index b12fe9a534..5a922dd857 100644
--- a/toolkit/components/startup/moz.build
+++ b/toolkit/components/startup/moz.build
@@ -7,7 +7,7 @@ DIRS += ['public']
 
 EXPORTS.mozilla += ['StartupTimeline.h']
 
-UNIFIED_SOURCES += [
+SOURCES += [
     'nsAppStartup.cpp',
     'StartupTimeline.cpp',
 ]
@@ -17,8 +17,8 @@ if CONFIG['MOZ_USERINFO']:
         # This file cannot be built in unified mode because of name clashes with Windows headers.
         SOURCES += ['nsUserInfoWin.cpp']
     elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
-        UNIFIED_SOURCES += ['nsUserInfoMac.mm']
+        SOURCES += ['nsUserInfoMac.mm']
     else:
-        UNIFIED_SOURCES += ['nsUserInfoUnix.cpp']
+        SOURCES += ['nsUserInfoUnix.cpp']
 
 FINAL_LIBRARY = 'xul'