diff --git a/hledger-lib/Hledger/Data/Types.hs b/hledger-lib/Hledger/Data/Types.hs
index cb2b8d180..7e845cd72 100644
--- a/hledger-lib/Hledger/Data/Types.hs
+++ b/hledger-lib/Hledger/Data/Types.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP, DeriveDataTypeable, StandaloneDeriving, DeriveAnyClass, DeriveGeneric, TypeSynonymInstances, FlexibleInstances #-}
+{-# LANGUAGE CPP, DeriveDataTypeable, StandaloneDeriving, DeriveGeneric, TypeSynonymInstances, FlexibleInstances #-}
 {-|
 
 Most data types are defined here to avoid import cycles.
@@ -39,21 +39,29 @@ type SmartDate = (String,String,String)
 
 data WhichDate = PrimaryDate | SecondaryDate deriving (Eq,Show)
 
-data DateSpan = DateSpan (Maybe Day) (Maybe Day) deriving (Eq,Ord,Data,NFData,Generic,Typeable)
+data DateSpan = DateSpan (Maybe Day) (Maybe Day) deriving (Eq,Ord,Data,Generic,Typeable)
+
+instance NFData DateSpan
 
 data Interval = NoInterval
               | Days Int | Weeks Int | Months Int | Quarters Int | Years Int
               | DayOfMonth Int | DayOfWeek Int
               -- WeekOfYear Int | MonthOfYear Int | QuarterOfYear Int
-                deriving (Eq,Show,Ord,Data,NFData,Generic,Typeable)
+                deriving (Eq,Show,Ord,Data,Generic,Typeable)
+
+instance NFData Interval
 
 type AccountName = String
 
 data AccountAlias = BasicAlias AccountName AccountName
                   | RegexAlias Regexp Replacement
-  deriving (Eq, Read, Show, Ord, Data, NFData,Generic, Typeable)
+  deriving (Eq, Read, Show, Ord, Data, Generic, Typeable)
 
-data Side = L | R deriving (Eq,Show,Read,Ord,Typeable,Data,NFData,Generic)
+instance NFData AccountAlias
+
+data Side = L | R deriving (Eq,Show,Read,Ord,Typeable,Data,Generic)
+
+instance NFData Side
 
 type Commodity = String
 
@@ -76,7 +84,9 @@ numberRepresentation = "Decimal"
 
 -- | An amount's price (none, per unit, or total) in another commodity.
 -- Note the price should be a positive number, although this is not enforced.
-data Price = NoPrice | UnitPrice Amount | TotalPrice Amount deriving (Eq,Ord,Typeable,Data,NFData,Generic)
+data Price = NoPrice | UnitPrice Amount | TotalPrice Amount deriving (Eq,Ord,Typeable,Data,Generic)
+
+instance NFData Price
 
 -- | Display style for an amount.
 data AmountStyle = AmountStyle {
@@ -85,7 +95,9 @@ data AmountStyle = AmountStyle {
       asprecision :: Int,            -- ^ number of digits displayed after the decimal point
       asdecimalpoint :: Maybe Char,  -- ^ character used as decimal point: period or comma. Nothing means "unspecified, use default"
       asdigitgroups :: Maybe DigitGroupStyle -- ^ style for displaying digit groups, if any
-} deriving (Eq,Ord,Read,Show,Typeable,Data,NFData,Generic)
+} deriving (Eq,Ord,Read,Show,Typeable,Data,Generic)
+
+instance NFData AmountStyle
 
 -- | A style for displaying digit groups in the integer part of a
 -- floating point number. It consists of the character used to
@@ -94,24 +106,34 @@ data AmountStyle = AmountStyle {
 -- the decimal point. The last group size is assumed to repeat. Eg,
 -- comma between thousands is DigitGroups ',' [3].
 data DigitGroupStyle = DigitGroups Char [Int]
-  deriving (Eq,Ord,Read,Show,Typeable,Data,NFData,Generic)
+  deriving (Eq,Ord,Read,Show,Typeable,Data,Generic)
+
+instance NFData DigitGroupStyle
 
 data Amount = Amount {
       acommodity :: Commodity,
       aquantity :: Quantity,
       aprice :: Price,                -- ^ the (fixed) price for this amount, if any
       astyle :: AmountStyle
-    } deriving (Eq,Ord,Typeable,Data,NFData,Generic)
+    } deriving (Eq,Ord,Typeable,Data,Generic)
 
-newtype MixedAmount = Mixed [Amount] deriving (Eq,Ord,Typeable,Data,NFData,Generic)
+instance NFData Amount
+
+newtype MixedAmount = Mixed [Amount] deriving (Eq,Ord,Typeable,Data,Generic)
+
+instance NFData MixedAmount
 
 data PostingType = RegularPosting | VirtualPosting | BalancedVirtualPosting
-                   deriving (Eq,Show,Typeable,Data,NFData,Generic)
+                   deriving (Eq,Show,Typeable,Data,Generic)
+
+instance NFData PostingType
 
 type Tag = (String, String)  -- ^ A tag name and (possibly empty) value.
 
 data ClearedStatus = Uncleared | Pending | Cleared
-                   deriving (Eq,Ord,Typeable,Data,NFData,Generic)
+                   deriving (Eq,Ord,Typeable,Data,Generic)
+
+instance NFData ClearedStatus
 
 instance Show ClearedStatus where -- custom show
   show Uncleared = ""             -- a bad idea
@@ -130,7 +152,9 @@ data Posting = Posting {
       pbalanceassertion :: Maybe MixedAmount,  -- ^ optional: the expected balance in the account after this posting
       ptransaction :: Maybe Transaction    -- ^ this posting's parent transaction (co-recursive types).
                                            -- Tying this knot gets tedious, Maybe makes it easier/optional.
-    } deriving (Typeable,Data,NFData,Generic)
+    } deriving (Typeable,Data,Generic)
+
+instance NFData Posting
 
 -- The equality test for postings ignores the parent transaction's
 -- identity, to avoid infinite loops.
@@ -140,7 +164,9 @@ instance Eq Posting where
 -- | The position of parse errors (eg), like parsec's SourcePos but generic.
 -- File name, 1-based line number and 1-based column number.
 data GenericSourcePos = GenericSourcePos FilePath Int Int
-  deriving (Eq, Read, Show, Ord, Data, NFData, Generic, Typeable)
+  deriving (Eq, Read, Show, Ord, Data, Generic, Typeable)
+
+instance NFData GenericSourcePos
 
 data Transaction = Transaction {
       tsourcepos :: GenericSourcePos,
@@ -153,19 +179,27 @@ data Transaction = Transaction {
       ttags :: [Tag], -- ^ tag names and values, extracted from the comment
       tpostings :: [Posting],            -- ^ this transaction's postings
       tpreceding_comment_lines :: String -- ^ any comment lines immediately preceding this transaction
-    } deriving (Eq,Typeable,Data,NFData,Generic)
+    } deriving (Eq,Typeable,Data,Generic)
+
+instance NFData Transaction
 
 data ModifierTransaction = ModifierTransaction {
       mtvalueexpr :: String,
       mtpostings :: [Posting]
-    } deriving (Eq,Typeable,Data,NFData,Generic)
+    } deriving (Eq,Typeable,Data,Generic)
+
+instance NFData ModifierTransaction
 
 data PeriodicTransaction = PeriodicTransaction {
       ptperiodicexpr :: String,
       ptpostings :: [Posting]
-    } deriving (Eq,Typeable,Data,NFData,Generic)
+    } deriving (Eq,Typeable,Data,Generic)
 
-data TimeLogCode = SetBalance | SetRequiredHours | In | Out | FinalOut deriving (Eq,Ord,Typeable,Data,NFData,Generic)
+instance NFData PeriodicTransaction
+
+data TimeLogCode = SetBalance | SetRequiredHours | In | Out | FinalOut deriving (Eq,Ord,Typeable,Data,Generic)
+
+instance NFData TimeLogCode
 
 data TimeLogEntry = TimeLogEntry {
       tlsourcepos :: GenericSourcePos,
@@ -173,13 +207,17 @@ data TimeLogEntry = TimeLogEntry {
       tldatetime :: LocalTime,
       tlaccount :: String,
       tldescription :: String
-    } deriving (Eq,Ord,Typeable,Data,NFData,Generic)
+    } deriving (Eq,Ord,Typeable,Data,Generic)
+
+instance NFData TimeLogEntry
 
 data HistoricalPrice = HistoricalPrice {
       hdate :: Day,
       hcommodity :: Commodity,
       hamount :: Amount
-    } deriving (Eq,Typeable,Data, NFData,Generic) -- & Show (in Amount.hs)
+    } deriving (Eq,Typeable,Data,Generic) -- & Show (in Amount.hs)
+
+instance NFData HistoricalPrice
 
 type Year = Integer
 
@@ -194,13 +232,16 @@ data JournalContext = Ctx {
                                         --   specified with "account" directive(s). Concatenated, these
                                         --   are the account prefix prepended to parsed account names.
     , ctxAliases   :: ![AccountAlias]   -- ^ the current list of account name aliases in effect
-    } deriving (Read, Show, Eq, Data, Typeable, NFData,Generic)
+    } deriving (Read, Show, Eq, Data, Typeable, Generic)
+
+instance NFData JournalContext
 
 deriving instance Data (ClockTime)
 deriving instance Typeable (ClockTime)
-deriving instance NFData (ClockTime)
 deriving instance Generic (ClockTime)
 
+instance NFData ClockTime
+
 data Journal = Journal {
       jmodifiertxns :: [ModifierTransaction],
       jperiodictxns :: [PeriodicTransaction],
@@ -215,7 +256,9 @@ data Journal = Journal {
                                             -- order encountered.
       filereadtime :: ClockTime,            -- ^ when this journal was last read from its file(s)
       jcommoditystyles :: M.Map Commodity AmountStyle  -- ^ how to display amounts in each commodity
-    } deriving (Eq, Typeable, Data, NFData,Generic)
+    } deriving (Eq, Typeable, Data, Generic)
+
+instance NFData Journal
 
 -- | A JournalUpdate is some transformation of a Journal. It can do I/O or
 -- raise an error.
diff --git a/hledger-lib/hledger-lib.cabal b/hledger-lib/hledger-lib.cabal
index 770dd9118..0a7ee09dd 100644
--- a/hledger-lib/hledger-lib.cabal
+++ b/hledger-lib/hledger-lib.cabal
@@ -98,6 +98,7 @@ library
                  ,csv
                  -- ,data-pprint >= 0.2.3 && < 0.3
                  ,Decimal
+                 ,deepseq
                  ,directory
                  ,filepath
                  ,mtl
@@ -135,6 +136,7 @@ test-suite tests
                , csv
                -- , data-pprint >= 0.2.3 && < 0.3
                , Decimal
+               , deepseq
                , directory
                , filepath
                , HUnit