diff --git a/constants.cc b/constants.cc
index 4b87a58..f9c6ce5 100644
--- a/constants.cc
+++ b/constants.cc
@@ -10,4 +10,34 @@
   "/mnt/stateful_partition/factory_install_reset";
 
 const char kPowerwashCommand[] = "safe fast\n";
+
+
+// Constants defining keys for the persisted state of update engine.
+const char kPrefsBackoffExpiryTime[] = "backoff-expiry-time";
+const char kPrefsCertificateReportToSendDownload[] =
+    "certificate-report-to-send-download";
+const char kPrefsCertificateReportToSendUpdate[] =
+    "certificate-report-to-send-update";
+const char kPrefsCurrentResponseSignature[] = "current-response-signature";
+const char kPrefsCurrentUrlFailureCount[] = "current-url-failure-count";
+const char kPrefsCurrentUrlIndex[] = "current-url-index";
+const char kPrefsDeltaUpdateFailures[] = "delta-update-failures";
+const char kPrefsLastActivePingDay[] = "last-active-ping-day";
+const char kPrefsLastRollCallPingDay[] = "last-roll-call-ping-day";
+const char kPrefsManifestMetadataSize[] = "manifest-metadata-size";
+const char kPrefsPayloadAttemptNumber[] = "payload-attempt-number";
+const char kPrefsPreviousVersion[] = "previous-version";
+const char kPrefsResumedUpdateFailures[] = "resumed-update-failures";
+const char kPrefsUpdateCheckCount[] = "update-check-count";
+const char kPrefsUpdateCheckResponseHash[] = "update-check-response-hash";
+const char kPrefsUpdateFirstSeenAt[] = "update-first-seen-at";
+const char kPrefsUpdateServerCertificate[] = "update-server-cert";
+const char kPrefsUpdateStateNextDataOffset[] = "update-state-next-data-offset";
+const char kPrefsUpdateStateNextOperation[] = "update-state-next-operation";
+const char kPrefsUpdateStateSHA256Context[] = "update-state-sha-256-context";
+const char kPrefsUpdateStateSignatureBlob[] = "update-state-signature-blob";
+const char kPrefsUpdateStateSignedSHA256Context[] =
+    "update-state-signed-sha-256-context";
+const char kPrefsWallClockWaitPeriod[] = "wall-clock-wait-period";
+
 }