diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/Serialization.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/Serialization.hs
index e6d72c160cb..8589271eaa1 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/Serialization.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/Serialization.hs
@@ -175,7 +175,7 @@ decodeCollectionWithLen lenOrIndef el = do
     Nothing -> loop (0,[]) (not <$> decodeBreakOr) el
   where
   loop (n,acc) condition action = condition >>= \case
-      False -> pure (n,acc)
+      False -> pure (n,reverse acc)
       True -> action >>= \v -> loop (n+1, (v:acc)) condition action
 
 rationalToCBOR :: Rational -> Encoding