diff --git a/Ledger/Amount.hs b/Ledger/Amount.hs
index 7997df838..6ca89c492 100644
--- a/Ledger/Amount.hs
+++ b/Ledger/Amount.hs
@@ -47,6 +47,22 @@ import Ledger.Commodity
 instance Show Amount where show = showAmount
 -- instance Show MixedAmount where show = showMixedAmount
 
+instance Num Amount where
+    abs (Amount c q) = Amount c (abs q)
+    signum (Amount c q) = Amount c (signum q)
+    fromInteger i = Amount (comm "") (fromInteger i)
+    (+) = amountop (+)
+    (-) = amountop (-)
+    (*) = amountop (*)
+
+instance Num MixedAmount where
+    abs = error "programming error, mixed amounts do not support abs"
+    signum = error "programming error, mixed amounts do not support signum"
+    fromInteger i = [Amount (comm "") (fromInteger i)]
+    negate = map negate
+    (+) = (++)
+    (*) = error "programming error, mixed amounts do not support multiplication"
+
 showMixedAmount :: MixedAmount -> String
 showMixedAmount as = concat $ intersperse ", " $ map show $ normaliseMixedAmount as
 
@@ -60,9 +76,6 @@ groupAmountsByCommodity as = grouped
       hassymbol s a = s == (symbol $ commodity a)
       symbols = sort $ nub $ map (symbol . commodity) as
 
--- samecommoditysymbol Amount{commodity=c1} Amount{commodity=c2} = samesymbol c1 c2
--- samesymbol Commodity{symbol=s1} Commodity{symbol=s2} = s1==s2
-      
 -- | Get the string representation of an amount, based on its commodity's
 -- display settings.
 showAmount :: Amount -> String
@@ -91,6 +104,12 @@ showAmountOrZero a
     | isZeroAmount a = "0"
     | otherwise = showAmount a
 
+-- | Get the string representation of an amount, rounded, or showing just "0" if it's zero.
+showMixedAmountOrZero :: MixedAmount -> String
+showMixedAmountOrZero a
+    | isZeroMixedAmount a = "0"
+    | otherwise = showMixedAmount a
+
 -- | is this amount zero, when displayed with its given precision ?
 isZeroAmount :: Amount -> Bool
 isZeroAmount a@(Amount c _ ) = nonzerodigits == ""
@@ -99,14 +118,6 @@ isZeroAmount a@(Amount c _ ) = nonzerodigits == ""
 isZeroMixedAmount :: MixedAmount -> Bool
 isZeroMixedAmount = all isZeroAmount . normaliseMixedAmount
 
-instance Num Amount where
-    abs (Amount c q) = Amount c (abs q)
-    signum (Amount c q) = Amount c (signum q)
-    fromInteger i = Amount (comm "") (fromInteger i)
-    (+) = amountop (+)
-    (-) = amountop (-)
-    (*) = amountop (*)
-
 -- | Apply a binary arithmetic operator to two amounts, converting to the
 -- second one's commodity and adopting the lowest precision. (Using the
 -- second commodity means that folds (like sum [Amount]) will preserve the
@@ -128,7 +139,7 @@ sumAmounts = sum . filter (not . isZeroAmount)
 sumMixedAmounts :: [MixedAmount] -> MixedAmount
 sumMixedAmounts = concat
 
-nullamt = Amount (comm "") 0
+nullamt = []
 
 -- temporary value for partial entries
-autoamt = Amount (Commodity {symbol="AUTO",side=L,spaced=False,comma=False,precision=0,rate=1}) 0
+autoamt = [Amount (Commodity {symbol="AUTO",side=L,spaced=False,comma=False,precision=0,rate=1}) 0]
diff --git a/Ledger/Entry.hs b/Ledger/Entry.hs
index 457ba4e2a..72e9168b6 100644
--- a/Ledger/Entry.hs
+++ b/Ledger/Entry.hs
@@ -53,7 +53,7 @@ showEntry e =
       showtxn t = showacct t ++ "  " ++ (showamount $ tamount t) ++ (showcomment $ tcomment t)
       showtxnnoamt t = showacct t ++ "              " ++ (showcomment $ tcomment t)
       showacct t = "    " ++ (showaccountname $ taccount t)
-      showamount = printf "%12s" . showAmount
+      showamount = printf "%12s" . showMixedAmount
       showaccountname s = printf "%-34s" s
       showcomment s = if (length s) > 0 then "  ; "++s else ""
 
@@ -77,9 +77,9 @@ balanceEntry e@(Entry{etransactions=ts}) = e{etransactions=ts'}
               1 -> map balance ts
               otherwise -> error $ "could not balance this entry, too many missing amounts:\n" ++ show e
       otherstotal = sumRawTransactions withamounts
-      simpleotherstotal
-          | length otherstotal == 1 = head otherstotal
-          | otherwise = error $ "sorry, can't balance a mixed-commodity entry yet:\n" ++ show e
+--       simpleotherstotal
+--           | length otherstotal == 1 = head otherstotal
+--           | otherwise = error $ "sorry, can't balance a mixed-commodity entry yet:\n" ++ show e
       balance t
-          | isReal t && not (hasAmount t) = t{tamount = -simpleotherstotal}
+          | isReal t && not (hasAmount t) = t{tamount = -otherstotal}
           | otherwise = t
diff --git a/Ledger/Parse.hs b/Ledger/Parse.hs
index 7fe6236f7..b63c22307 100644
--- a/Ledger/Parse.hs
+++ b/Ledger/Parse.hs
@@ -301,7 +301,7 @@ ledgeraccountname = do
 accountnamechar = notFollowedBy (oneOf "()[]") >> nonspace
     <?> "account name character (non-bracket, non-parenthesis, non-whitespace)"
 
-transactionamount :: Parser Amount
+transactionamount :: Parser MixedAmount
 transactionamount =
   try (do
         many1 spacenonewline
@@ -309,29 +309,29 @@ transactionamount =
         return a
       ) <|> return autoamt
 
-leftsymbolamount :: Parser Amount
+leftsymbolamount :: Parser MixedAmount
 leftsymbolamount = do
   sym <- commoditysymbol 
   sp <- many spacenonewline
   (q,p,comma) <- amountquantity
   let c = Commodity {symbol=sym,side=L,spaced=not $ null sp,comma=comma,precision=p,rate=1}
-  return $ Amount c q
+  return [Amount c q]
   <?> "left-symbol amount"
 
-rightsymbolamount :: Parser Amount
+rightsymbolamount :: Parser MixedAmount
 rightsymbolamount = do
   (q,p,comma) <- amountquantity
   sp <- many spacenonewline
   sym <- commoditysymbol
   let c = Commodity {symbol=sym,side=R,spaced=not $ null sp,comma=comma,precision=p,rate=1}
-  return $ Amount c q
+  return [Amount c q]
   <?> "right-symbol amount"
 
-nosymbolamount :: Parser Amount
+nosymbolamount :: Parser MixedAmount
 nosymbolamount = do
   (q,p,comma) <- amountquantity
   let c = Commodity {symbol="",side=L,spaced=False,comma=comma,precision=p,rate=1}
-  return $ Amount c q
+  return [Amount c q]
   <?> "no-symbol amount"
 
 commoditysymbol :: Parser String
diff --git a/Ledger/RawLedger.hs b/Ledger/RawLedger.hs
index b983dfb60..9f999e1fe 100644
--- a/Ledger/RawLedger.hs
+++ b/Ledger/RawLedger.hs
@@ -11,6 +11,7 @@ import qualified Data.Map as Map
 import Ledger.Utils
 import Ledger.Types
 import Ledger.AccountName
+import Ledger.Amount
 import Ledger.Entry
 import Ledger.Transaction
 
@@ -104,10 +105,9 @@ normaliseRawLedgerAmounts l@(RawLedger ms ps es f) = RawLedger ms ps es' f
       normaliseEntryAmounts (Entry d s c desc comm ts pre) = Entry d s c desc comm ts' pre
           where ts' = map normaliseRawTransactionAmounts ts
       normaliseRawTransactionAmounts (RawTransaction acct a c t) = RawTransaction acct a' c t
-          where a' = normaliseAmount a
-      normaliseAmount (Amount c q) = Amount (firstoccurrenceof c) q
+          where a' = normaliseMixedAmount a
       firstcommodities = nubBy samesymbol $ allcommodities
-      allcommodities = map (commodity . amount) $ rawLedgerTransactions l
+      allcommodities = map commodity $ concat $ map amount $ rawLedgerTransactions l
       samesymbol (Commodity {symbol=s1}) (Commodity {symbol=s2}) = s1==s2
       firstoccurrenceof c@(Commodity {symbol=s}) = 
           fromMaybe
diff --git a/Ledger/RawTransaction.hs b/Ledger/RawTransaction.hs
index 863263ed3..1a47984ba 100644
--- a/Ledger/RawTransaction.hs
+++ b/Ledger/RawTransaction.hs
@@ -20,7 +20,7 @@ showRawTransaction (RawTransaction a amt _ ttype) =
     showaccountname a ++ " " ++ (showamount amt) 
     where
       showaccountname = printf "%-22s" . bracket . elideAccountName width
-      showamount = printf "%12s" . showAmountOrZero
+      showamount = printf "%12s" . showMixedAmountOrZero
       (bracket,width) = case ttype of
                       BalancedVirtualTransaction -> (\s -> "["++s++"]", 20)
                       VirtualTransaction -> (\s -> "("++s++")", 20)
@@ -30,7 +30,7 @@ isReal :: RawTransaction -> Bool
 isReal t = rttype t == RegularTransaction
 
 hasAmount :: RawTransaction -> Bool
-hasAmount = ("AUTO" /=) . symbol . commodity . tamount
+hasAmount = (/= autoamt) . tamount
 
 sumRawTransactions :: [RawTransaction] -> MixedAmount
-sumRawTransactions = normaliseMixedAmount . map tamount
+sumRawTransactions = normaliseMixedAmount . sumMixedAmounts . map tamount
diff --git a/Ledger/TimeLog.hs b/Ledger/TimeLog.hs
index 90c5e3f8c..18c5089b2 100644
--- a/Ledger/TimeLog.hs
+++ b/Ledger/TimeLog.hs
@@ -57,7 +57,7 @@ entryFromTimeLogInOut i o =
       showdate = formatTime defaultTimeLocale "%Y/%m/%d"
       intime   = parsedatetime $ tldatetime i
       outtime  = parsedatetime $ tldatetime o
-      amount   = hours $ realToFrac (diffUTCTime outtime intime) / 3600
+      amount   = [hours $ realToFrac (diffUTCTime outtime intime) / 3600]
       txns     = [RawTransaction acctname amount "" RegularTransaction
                  --,RawTransaction "assets:time" (-amount) "" RegularTransaction
                  ]
diff --git a/Ledger/Transaction.hs b/Ledger/Transaction.hs
index 2a2effb67..1ab69a271 100644
--- a/Ledger/Transaction.hs
+++ b/Ledger/Transaction.hs
@@ -30,7 +30,6 @@ accountNamesFromTransactions :: [Transaction] -> [AccountName]
 accountNamesFromTransactions ts = nub $ map account ts
 
 sumTransactions :: [Transaction] -> MixedAmount
--- sumTransactions = sum . map amount
-sumTransactions = map amount
+sumTransactions = sumMixedAmounts . map amount
 
 nulltxn = Transaction 0 "" "" "" nullamt RegularTransaction
diff --git a/Ledger/Types.hs b/Ledger/Types.hs
index 2ab131cb8..462f03d71 100644
--- a/Ledger/Types.hs
+++ b/Ledger/Types.hs
@@ -41,7 +41,7 @@ data TransactionType = RegularTransaction | VirtualTransaction | BalancedVirtual
 
 data RawTransaction = RawTransaction {
       taccount :: AccountName,
-      tamount :: Amount,
+      tamount :: MixedAmount,
       tcomment :: String,
       rttype :: TransactionType
     } deriving (Eq)
@@ -90,7 +90,7 @@ data Transaction = Transaction {
       date :: Date,
       description :: String,
       account :: AccountName,
-      amount :: Amount,
+      amount :: MixedAmount,
       ttype :: TransactionType
     } deriving (Eq)
 
diff --git a/RegisterCommand.hs b/RegisterCommand.hs
index f052b04d5..12e70b9d3 100644
--- a/RegisterCommand.hs
+++ b/RegisterCommand.hs
@@ -35,19 +35,19 @@ showRegisterReport opts args l = showtxns ts nulltxn nullamt
       -- show transactions, one per line, with a running balance
       showtxns [] _ _ = ""
       showtxns (t@Transaction{amount=a}:ts) tprev bal =
-          (if isZeroAmount a then "" else this) ++ showtxns ts t bal'
+          (if isZeroMixedAmount a then "" else this) ++ showtxns ts t bal'
           where
             this = showtxn (t `issame` tprev) t bal'
             issame t1 t2 = entryno t1 == entryno t2
             bal' = bal + amount t
 
       -- show one transaction line, with or without the entry details
-      showtxn :: Bool -> Transaction -> Amount -> String
+      showtxn :: Bool -> Transaction -> MixedAmount -> String
       showtxn omitdesc t b = entrydesc ++ txn ++ bal ++ "\n"
           where
             entrydesc = if omitdesc then replicate 32 ' ' else printf "%s %s " date desc
             date = showDate $ da
             desc = printf "%-20s" $ elideRight 20 de :: String
             txn = showRawTransaction $ RawTransaction a amt "" tt
-            bal = printf " %12s" (showAmountOrZero b)
+            bal = printf " %12s" (showMixedAmountOrZero b)
             Transaction{date=da,description=de,account=a,amount=amt,ttype=tt} = t
diff --git a/Tests.hs b/Tests.hs
index 42c84b636..4287992c0 100644
--- a/Tests.hs
+++ b/Tests.hs
@@ -78,7 +78,7 @@ unittests = TestList [
   ,
   "balanceEntry"      ~: do
     assertequal
-      (dollars (-47.18))
+      [dollars (-47.18)]
       (tamount $ last $ etransactions $ balanceEntry entry1)
   ,
   "punctuatethousands"      ~: punctuatethousands "" @?= ""
@@ -103,8 +103,8 @@ unittests = TestList [
     assertequal 15 (length $ Map.keys $ accountmap $ cacheLedger rawledger7)
   ,
   "transactionamount"       ~: do
-    assertparseequal (dollars 47.18) (parsewith transactionamount " $47.18")
-    assertparseequal (Amount (Commodity {symbol="$",side=L,spaced=False,comma=False,precision=0,rate=1}) 1) (parsewith transactionamount " $1.")
+    assertparseequal [dollars 47.18] (parsewith transactionamount " $47.18")
+    assertparseequal [Amount (Commodity {symbol="$",side=L,spaced=False,comma=False,precision=0,rate=1}) 1] (parsewith transactionamount " $1.")
   ]
 
 ------------------------------------------------------------------------------
@@ -215,7 +215,7 @@ balancecommandtests = TestList [
  ]
 
 registercommandtests = TestList [
-  "register does something" ~:
+  "register report" ~:
   do 
     l <- ledgerfromfile "sample.ledger"
     assertequal (
@@ -243,7 +243,7 @@ assertparseequal expected parsed = either printParseError (assertequal expected)
 
 rawtransaction1_str  = "  expenses:food:dining  $10.00\n"
 
-rawtransaction1 = RawTransaction "expenses:food:dining" (dollars 10) "" RegularTransaction
+rawtransaction1 = RawTransaction "expenses:food:dining" [dollars 10] "" RegularTransaction
 
 entry1_str = "\
 \2007/01/28 coopportunity\n\
@@ -253,8 +253,8 @@ entry1_str = "\
 
 entry1 =
     (Entry "2007/01/28" False "" "coopportunity" ""
-     [RawTransaction "expenses:food:groceries" (dollars 47.18) "" RegularTransaction, 
-      RawTransaction "assets:checking" (dollars (-47.18)) "" RegularTransaction] "")
+     [RawTransaction "expenses:food:groceries" [dollars 47.18] "" RegularTransaction, 
+      RawTransaction "assets:checking" [dollars (-47.18)] "" RegularTransaction] "")
 
 
 entry2_str = "\
@@ -398,13 +398,13 @@ rawledger7 = RawLedger
              etransactions=[
               RawTransaction {
                 taccount="assets:cash", 
-                tamount=dollars 4.82,
+                tamount=[dollars 4.82],
                 tcomment="",
                 rttype=RegularTransaction
               },
               RawTransaction {
                 taccount="equity:opening balances", 
-                tamount=dollars (-4.82),
+                tamount=[dollars (-4.82)],
                 tcomment="",
                 rttype=RegularTransaction
               }
@@ -421,13 +421,13 @@ rawledger7 = RawLedger
              etransactions=[
               RawTransaction {
                 taccount="expenses:vacation", 
-                tamount=dollars 179.92,
+                tamount=[dollars 179.92],
                 tcomment="",
                 rttype=RegularTransaction
               },
               RawTransaction {
                 taccount="assets:checking", 
-                tamount=dollars (-179.92),
+                tamount=[dollars (-179.92)],
                 tcomment="",
                 rttype=RegularTransaction
               }
@@ -444,13 +444,13 @@ rawledger7 = RawLedger
              etransactions=[
               RawTransaction {
                 taccount="assets:saving", 
-                tamount=dollars 200,
+                tamount=[dollars 200],
                 tcomment="",
                 rttype=RegularTransaction
               },
               RawTransaction {
                 taccount="assets:checking", 
-                tamount=dollars (-200),
+                tamount=[dollars (-200)],
                 tcomment="",
                 rttype=RegularTransaction
               }
@@ -467,13 +467,13 @@ rawledger7 = RawLedger
              etransactions=[
               RawTransaction {
                 taccount="expenses:food:dining", 
-                tamount=dollars 4.82,
+                tamount=[dollars 4.82],
                 tcomment="",
                 rttype=RegularTransaction
               },
               RawTransaction {
                 taccount="assets:cash", 
-                tamount=dollars (-4.82),
+                tamount=[dollars (-4.82)],
                 tcomment="",
                 rttype=RegularTransaction
               }
@@ -490,13 +490,13 @@ rawledger7 = RawLedger
              etransactions=[
               RawTransaction {
                 taccount="expenses:phone", 
-                tamount=dollars 95.11,
+                tamount=[dollars 95.11],
                 tcomment="",
                 rttype=RegularTransaction
               },
               RawTransaction {
                 taccount="assets:checking", 
-                tamount=dollars (-95.11),
+                tamount=[dollars (-95.11)],
                 tcomment="",
                 rttype=RegularTransaction
               }
@@ -513,13 +513,13 @@ rawledger7 = RawLedger
              etransactions=[
               RawTransaction {
                 taccount="liabilities:credit cards:discover", 
-                tamount=dollars 80,
+                tamount=[dollars 80],
                 tcomment="",
                 rttype=RegularTransaction
               },
               RawTransaction {
                 taccount="assets:checking", 
-                tamount=dollars (-80),
+                tamount=[dollars (-80)],
                 tcomment="",
                 rttype=RegularTransaction
               }