diff --git a/substrate/frame/aura/src/lib.rs b/substrate/frame/aura/src/lib.rs
index 997f51ba42..3ca1444aaa 100644
--- a/substrate/frame/aura/src/lib.rs
+++ b/substrate/frame/aura/src/lib.rs
@@ -114,6 +114,7 @@ pub mod pallet {
 		/// The effective value of this type should not change while the chain is running.
 		///
 		/// For backwards compatibility either use [`MinimumPeriodTimesTwo`] or a const.
+		#[pallet::constant]
 		type SlotDuration: Get<<Self as pallet_timestamp::Config>::Moment>;
 	}