diff --git a/constants.h b/constants.h
index 4bd9685..f2dfc5a 100644
--- a/constants.h
+++ b/constants.h
@@ -37,6 +37,7 @@
 extern const char kPrefsPayloadAttemptNumber[];
 extern const char kPrefsPreviousVersion[];
 extern const char kPrefsResumedUpdateFailures[];
+extern const char kPrefsSystemUpdatedMarker[];
 extern const char kPrefsTotalBytesDownloaded[];
 extern const char kPrefsUpdateCheckCount[];
 extern const char kPrefsUpdateCheckResponseHash[];