diff --git a/hardware_chromeos.h b/hardware_chromeos.h
index 03ad750..a756a9b 100644
--- a/hardware_chromeos.h
+++ b/hardware_chromeos.h
@@ -51,6 +51,7 @@
   bool CancelPowerwash() override;
   bool GetNonVolatileDirectory(base::FilePath* path) const override;
   bool GetPowerwashSafeDirectory(base::FilePath* path) const override;
+  int64_t GetBuildTimestamp() const override;
 
  private:
   friend class HardwareChromeOSTest;