diff --git a/hardware_chromeos.h b/hardware_chromeos.h
index 8829866..57be3b0 100644
--- a/hardware_chromeos.h
+++ b/hardware_chromeos.h
@@ -58,6 +58,7 @@
   bool GetNonVolatileDirectory(base::FilePath* path) const override;
   bool GetPowerwashSafeDirectory(base::FilePath* path) const override;
   int64_t GetBuildTimestamp() const override;
+  bool AllowDowngrade() const override { return false; }
   bool GetFirstActiveOmahaPingSent() const override;
   bool SetFirstActiveOmahaPingSent() override;