diff --git a/src/Ledger/Prelude.agda b/src/Ledger/Prelude.agda
index 2b56acfee..6bc011190 100644
--- a/src/Ledger/Prelude.agda
+++ b/src/Ledger/Prelude.agda
@@ -86,6 +86,7 @@ open import Axiom.Set.Map th public
   renaming (Map to _⇀_)
 
 open import Axiom.Set.TotalMap th public
+open import Axiom.Set.TotalMapOn th
 
 open L.Decˡ public
   hiding (_∈?_; ≟-∅)