diff --git a/update_engine.gyp b/update_engine.gyp
index 3fcb706..9b97e71 100644
--- a/update_engine.gyp
+++ b/update_engine.gyp
@@ -20,8 +20,10 @@
         'libbrillo-<(libbase_ver)',
         'libchrome-<(libbase_ver)',
       ],
-      # Defaults if the -DUSE_* flags are not passed to gyp is 0. You can set
-      # the default value for the USE flag in the ebuild.
+      # The -DUSE_* flags are passed from platform2.py. We use sane defaults
+      # here when these USE flags are not defined. You can set the default value
+      # for the USE flag in the ebuild.
+      'USE_dbus%': '1',
       'USE_hwid_override%': '0',
       'USE_mtd%': '0',
       'USE_power_management%': '0',