diff --git a/phosphor-power-supply/power_supply.hpp b/phosphor-power-supply/power_supply.hpp
index 320fb65..ec523ae 100644
--- a/phosphor-power-supply/power_supply.hpp
+++ b/phosphor-power-supply/power_supply.hpp
@@ -26,6 +26,7 @@
 // The D-Bus property name to update with the CCIN value.
 constexpr auto MODEL_PROP = "Model";
 constexpr auto PN_PROP = "PartNumber";
+constexpr auto SPARE_PN_PROP = "SparePartNumber";
 constexpr auto SN_PROP = "SerialNumber";
 constexpr auto VERSION_PROP = "Version";