diff --git a/hledger-lib/Hledger/Data/Posting.hs b/hledger-lib/Hledger/Data/Posting.hs
index d69fad04d..d603e2ac9 100644
--- a/hledger-lib/Hledger/Data/Posting.hs
+++ b/hledger-lib/Hledger/Data/Posting.hs
@@ -37,6 +37,7 @@ module Hledger.Data.Posting (
   joinAccountNames,
   concatAccountNames,
   accountNameApplyAliases,
+  accountNameApplyAliasesMemo,
   -- * arithmetic
   sumPostings,
   -- * rendering
@@ -231,6 +232,10 @@ accountNameApplyAliases aliases a = accountNameWithPostingType atype aname'
              aname
              aliases
 
+-- | Memoising version of accountNameApplyAliases, maybe overkill.
+accountNameApplyAliasesMemo :: [AccountAlias] -> AccountName -> AccountName
+accountNameApplyAliasesMemo aliases = memo (accountNameApplyAliases aliases)
+
 -- aliasMatches :: AccountAlias -> AccountName -> Bool
 -- aliasMatches (BasicAlias old _) a = old `isAccountNamePrefixOf` a
 -- aliasMatches (RegexAlias re  _) a = regexMatchesCI re a
diff --git a/hledger-lib/Hledger/Read/JournalReader.hs b/hledger-lib/Hledger/Read/JournalReader.hs
index 76c1b1663..a00d51839 100644
--- a/hledger-lib/Hledger/Read/JournalReader.hs
+++ b/hledger-lib/Hledger/Read/JournalReader.hs
@@ -664,6 +664,7 @@ modifiedaccountnamep = do
   a <- accountnamep
   return $
     accountNameApplyAliases aliases $
+     -- XXX accountNameApplyAliasesMemo ? doesn't seem to make a difference
     joinAccountNames parent
     a