diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 1.9.7
+
+- Drop support for GHCs prior 8.6.5
+
 # 1.9.6.1
 
 - Support `time-1.12`.
diff --git a/src/Data/Format.hs b/src/Data/Format.hs
--- a/src/Data/Format.hs
+++ b/src/Data/Format.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 module Data.Format
     ( Productish(..)
     , Summish(..)
@@ -23,24 +22,12 @@
     , decimalFormat
     ) where
 
-#if MIN_VERSION_base(4,9,0)
 import Control.Monad.Fail
 import Prelude hiding (fail)
-#endif
-#if MIN_VERSION_base(4,8,0)
 import Data.Void
-#endif
 import Data.Char
 import Text.ParserCombinators.ReadP
 
-
-#if MIN_VERSION_base(4,8,0)
-#else
-data Void
-absurd :: Void -> a
-absurd v = seq v $ error "absurd"
-#endif
-
 class IsoVariant f where
     isoMap :: (a -> b) -> (b -> a) -> f a -> f b
 
@@ -63,11 +50,7 @@
 
 
 parseReader :: (
-#if MIN_VERSION_base(4,9,0)
     MonadFail m
-#else
-    Monad m
-#endif
     ) => ReadP t -> String -> m t
 parseReader readp s = case [ t | (t,"") <- readP_to_S readp s] of
     [t] -> return t
@@ -90,11 +73,7 @@
 
 -- | Parse a value in the format
 formatParseM :: (
-#if MIN_VERSION_base(4,9,0)
     MonadFail m
-#else
-    Monad m
-#endif
     ) => Format t -> String -> m t
 formatParseM format = parseReader $ formatReadP format
 
diff --git a/src/Data/Time/Calendar/Compat.hs b/src/Data/Time/Calendar/Compat.hs
--- a/src/Data/Time/Calendar/Compat.hs
+++ b/src/Data/Time/Calendar/Compat.hs
@@ -1,9 +1,7 @@
 {-# LANGUAGE CPP                #-}
 {-# LANGUAGE DeriveDataTypeable #-}
-#if __GLASGOW_HASKELL__ >= 710
 {-# LANGUAGE PatternSynonyms    #-}
 {-# LANGUAGE ViewPatterns       #-}
-#endif
 module Data.Time.Calendar.Compat (
     -- * Days
     Day(..),addDays,diffDays,
@@ -31,9 +29,7 @@
 
     -- * Type aliases
     DayOfMonth, MonthOfYear, Year,
-#if __GLASGOW_HASKELL__ >= 710
     pattern YearMonthDay,
-#endif
     ) where
 
 import Data.Time.Calendar
@@ -48,10 +44,6 @@
 import Data.Time.Calendar.WeekDate.Compat
 #endif
 
-#if !MIN_VERSION_time(1,5,0)
-import System.Locale (TimeLocale (..))
-#endif
-
 import Control.DeepSeq (NFData (..))
 import Data.Data       (Data, Typeable)
 import Data.Monoid     (Monoid (..))
@@ -71,14 +63,7 @@
 data CalendarDiffDays = CalendarDiffDays
     { cdMonths :: Integer
     , cdDays :: Integer
-    } deriving (Eq,
-    Data
-#if __GLASGOW_HASKELL__ >= 802
-#endif
-    ,Typeable
-#if __GLASGOW_HASKELL__ >= 802
-#endif
-    )
+    } deriving (Eq, Data, Typeable)
 
 -- | Additive
 instance Semigroup CalendarDiffDays where
@@ -161,17 +146,13 @@
 #endif
 
 #if !MIN_VERSION_time(1,11,0)
-#if __GLASGOW_HASKELL__ >= 710
 -- | Bidirectional abstract constructor for the proleptic Gregorian calendar.
 -- Invalid values will be clipped to the correct range, month first, then day.
 pattern YearMonthDay :: Year -> MonthOfYear -> DayOfMonth -> Day
 pattern YearMonthDay y m d <- (toGregorian -> (y,m,d)) where
     YearMonthDay y m d = fromGregorian y m d
 
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE YearMonthDay #-}
-#endif
-#endif
 #endif
 
 -------------------------------------------------------------------------------
diff --git a/src/Data/Time/Calendar/Julian/Compat.hs b/src/Data/Time/Calendar/Julian/Compat.hs
--- a/src/Data/Time/Calendar/Julian/Compat.hs
+++ b/src/Data/Time/Calendar/Julian/Compat.hs
@@ -1,8 +1,6 @@
 {-# LANGUAGE CPP #-}
-#if __GLASGOW_HASKELL__ >= 710
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE ViewPatterns    #-}
-#endif
 module Data.Time.Calendar.Julian.Compat (
     Year, MonthOfYear, DayOfMonth, DayOfYear,
 
@@ -14,9 +12,7 @@
     isJulianLeapYear,
 
     toJulian,fromJulian,
-#if __GLASGOW_HASKELL__ >= 710
     pattern JulianYearMonthDay,
-#endif
     fromJulianValid,showJulian,julianMonthLength,
 
     -- calendrical arithmetic
@@ -80,15 +76,11 @@
 #endif
 
 #if !MIN_VERSION_time(1,11,0)
-#if __GLASGOW_HASKELL__ >= 710
 -- | Bidirectional abstract constructor for the proleptic Julian calendar.
 -- Invalid values will be clipped to the correct range, month first, then day.
 pattern JulianYearMonthDay :: Year -> MonthOfYear -> DayOfMonth -> Day
 pattern JulianYearMonthDay y m d <- (toJulian -> (y,m,d)) where
     JulianYearMonthDay y m d = fromJulian y m d
 
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE JulianYearMonthDay #-}
-#endif
-#endif
 #endif
diff --git a/src/Data/Time/Calendar/Month/Compat.hs b/src/Data/Time/Calendar/Month/Compat.hs
--- a/src/Data/Time/Calendar/Month/Compat.hs
+++ b/src/Data/Time/Calendar/Month/Compat.hs
@@ -1,18 +1,12 @@
 {-# LANGUAGE CPP                #-}
 {-# LANGUAGE DeriveDataTypeable #-}
-#if __GLASGOW_HASKELL__ >= 710
 {-# LANGUAGE PatternSynonyms    #-}
 {-# LANGUAGE ViewPatterns       #-}
-#endif
 module Data.Time.Calendar.Month.Compat (
     Month(..), addMonths, diffMonths,
-#if __GLASGOW_HASKELL__ >= 710
     pattern YearMonth,
-#endif
     fromYearMonthValid,
-#if __GLASGOW_HASKELL__ >= 710
     pattern MonthDay,
-#endif
     fromMonthDayValid,
     -- * time-compat extras
     fromYearMonth,
@@ -113,10 +107,8 @@
 
 #if MIN_VERSION_time(1,9,0)
 #define FORMAT_OPTS fo
-#elif MIN_VERSION_time(1,8,0)
-#define FORMAT_OPTS tl mpo i
 #else
-#define FORMAT_OPTS tl mpo
+#define FORMAT_OPTS tl mpo i
 #endif
 
 #if MIN_VERSION_time(1,9,0)
@@ -158,17 +150,13 @@
 toYearMonth (MkMonth m) = case divMod' m 12 of
     (y, my) -> (y, succ (fromInteger my))
 
-#if __GLASGOW_HASKELL__ >= 710
 -- | Bidirectional abstract constructor.
 -- Invalid months of year will be clipped to the correct range.
 pattern YearMonth :: Year -> MonthOfYear -> Month
 pattern YearMonth y my <- (toYearMonth -> (y, my))
   where YearMonth y my = fromYearMonth y my
 
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE YearMonth #-}
-#endif
-#endif
 
 -- | Part of 'MonthDay' pattern
 toMonthDay :: Day -> (Month,DayOfMonth)
@@ -184,17 +172,12 @@
 fromMonthDayValid m dm = case toYearMonth m of
     (y, my) -> fromGregorianValid y my dm
 
-#if __GLASGOW_HASKELL__ >= 710
 -- | Bidirectional abstract constructor.
 -- Invalid days of month will be clipped to the correct range.
 pattern MonthDay :: Month -> DayOfMonth -> Day
 pattern MonthDay m dm <- (toMonthDay -> (m,dm)) where
     MonthDay (YearMonth y my) dm = fromGregorian y my dm
 
-
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE MonthDay #-}
-#endif
-#endif
 
 #endif
diff --git a/src/Data/Time/Calendar/MonthDay/Compat.hs b/src/Data/Time/Calendar/MonthDay/Compat.hs
--- a/src/Data/Time/Calendar/MonthDay/Compat.hs
+++ b/src/Data/Time/Calendar/MonthDay/Compat.hs
@@ -1,12 +1,8 @@
 {-# LANGUAGE CPP #-}
-#if __GLASGOW_HASKELL__ >= 710
 {-# LANGUAGE PatternSynonyms #-}
-#endif
 module Data.Time.Calendar.MonthDay.Compat (
     MonthOfYear, DayOfMonth, DayOfYear,
-#if __GLASGOW_HASKELL__ >= 710
     -- patterns
-#endif
     monthAndDayToDayOfYear,
     monthAndDayToDayOfYearValid,
     dayOfYearToMonthAndDay,
@@ -23,7 +19,6 @@
 
 {-
 #if !MIN_VERSION_time(1,12,0)
-#if __GLASGOW_HASKELL__ >= 710
 pattern January :: MonthOfYear
 pattern January = 1
 
@@ -61,9 +56,6 @@
 pattern December :: MonthOfYear
 pattern December = 12
 
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE January, February, March, April, May, June, July, August, September, October, November, December #-}
-#endif
-#endif
 #endif
 -}
diff --git a/src/Data/Time/Calendar/OrdinalDate/Compat.hs b/src/Data/Time/Calendar/OrdinalDate/Compat.hs
--- a/src/Data/Time/Calendar/OrdinalDate/Compat.hs
+++ b/src/Data/Time/Calendar/OrdinalDate/Compat.hs
@@ -1,15 +1,11 @@
 {-# LANGUAGE CPP #-}
-#if __GLASGOW_HASKELL__ >= 710
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE ViewPatterns #-}
-#endif
 module Data.Time.Calendar.OrdinalDate.Compat (
     Day, Year, DayOfYear, WeekOfYear,
     toOrdinalDate,
     fromOrdinalDate,
-#if __GLASGOW_HASKELL__ >= 710
     pattern YearDay,
-#endif
     fromOrdinalDateValid,
     showOrdinalDate,
     isLeapYear,
@@ -24,11 +20,7 @@
 import Data.Time.Orphans ()
 
 import Data.Time.Calendar.OrdinalDate hiding (fromSundayStartWeekValid)
-#if MIN_VERSION_time(1,6,0)
 import Data.Time.Calendar.OrdinalDate (fromSundayStartWeekValid)
-#else
-import Data.Time.Calendar.Private
-#endif
 
 #if !MIN_VERSION_time(1,11,0)
 import Data.Time.Calendar
@@ -37,46 +29,12 @@
 
 #if !MIN_VERSION_time(1,11,0)
 
-#if __GLASGOW_HASKELL__ >= 710
 -- | Bidirectional abstract constructor for ISO 8601 Ordinal Date format.
 -- Invalid day numbers will be clipped to the correct range (1 to 365 or 366).
 pattern YearDay :: Year -> DayOfYear -> Day
 pattern YearDay y d <- (toOrdinalDate -> (y,d)) where
     YearDay y d = fromOrdinalDate y d
 
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE YearDay #-}
-#endif
-#endif
 
-#endif
-
-#if !MIN_VERSION_time(1,6,0)
-fromSundayStartWeekValid ::
-       Year -- ^ Year.
-    -> WeekOfYear -- ^ Sunday-starting week number (as @%U@ in 'Data.Time.Format.formatTime').
-    -> Int -- ^ Day of week.
-                               -- Sunday is 0, Saturday is 6 (as @%w@ in 'Data.Time.Format.formatTime').
-    -> Maybe Day
-fromSundayStartWeekValid year w d = do
-    d' <- clipValid 0 6 d
-    let
-        -- first day of the year
-        firstDay = fromOrdinalDate year 1
-        -- 0-based week of year
-        zbFirstSunday = (4 - toModifiedJulianDay firstDay) `mod` 7
-        -- 0-based week number
-        zbWeek = w - 1
-        -- 0-based day of week
-        zbDay = d'
-        -- 0-based day in year
-        zbYearDay = zbFirstSunday + 7 * toInteger zbWeek + toInteger zbDay
-    zbYearDay' <-
-        clipValid
-            0
-            (if isLeapYear year
-                 then 365
-                 else 364)
-            zbYearDay
-    return $ addDays zbYearDay' firstDay
 #endif
diff --git a/src/Data/Time/Calendar/Quarter/Compat.hs b/src/Data/Time/Calendar/Quarter/Compat.hs
--- a/src/Data/Time/Calendar/Quarter/Compat.hs
+++ b/src/Data/Time/Calendar/Quarter/Compat.hs
@@ -1,15 +1,11 @@
 {-# LANGUAGE CPP                #-}
 {-# LANGUAGE DeriveDataTypeable #-}
-#if __GLASGOW_HASKELL__ >= 710
 {-# LANGUAGE PatternSynonyms    #-}
 {-# LANGUAGE ViewPatterns       #-}
-#endif
 module Data.Time.Calendar.Quarter.Compat (
     QuarterOfYear(..), addQuarters, diffQuarters,
     Quarter(..),
-#if __GLASGOW_HASKELL__ >= 710
     pattern YearQuarter,
-#endif
     monthOfYearQuarter,
     monthQuarter,
     dayQuarter,
@@ -122,16 +118,12 @@
 diffQuarters :: Quarter -> Quarter -> Integer
 diffQuarters (MkQuarter a) (MkQuarter b) = a - b
 
-#if __GLASGOW_HASKELL__ >= 710
 -- | Bidirectional abstract constructor.
 pattern YearQuarter :: Year -> QuarterOfYear -> Quarter
 pattern YearQuarter y qy <- (toYearQuarter -> (y, qy))
   where YearQuarter y qy = fromYearQuarter y qy
 
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE YearQuarter #-}
-#endif
-#endif
 
 monthOfYearQuarter :: MonthOfYear -> QuarterOfYear
 monthOfYearQuarter my | my <= 3 = Q1
diff --git a/src/Data/Time/Calendar/WeekDate/Compat.hs b/src/Data/Time/Calendar/WeekDate/Compat.hs
--- a/src/Data/Time/Calendar/WeekDate/Compat.hs
+++ b/src/Data/Time/Calendar/WeekDate/Compat.hs
@@ -1,10 +1,8 @@
 {-# LANGUAGE CPP                #-}
 {-# LANGUAGE BangPatterns       #-}
 {-# LANGUAGE DeriveDataTypeable #-}
-#if __GLASGOW_HASKELL__ >= 710
 {-# LANGUAGE PatternSynonyms    #-}
 {-# LANGUAGE ViewPatterns       #-}
-#endif
 module Data.Time.Calendar.WeekDate.Compat (
     Year, WeekOfYear, DayOfWeek(..), dayOfWeek,
     FirstWeekType (..),
@@ -16,9 +14,7 @@
     -- * ISO 8601 Week Date format
     toWeekDate,
     fromWeekDate,
-#if __GLASGOW_HASKELL__ >= 710
     pattern YearWeekDay,
-#endif
     fromWeekDateValid,
     showWeekDate,
 ) where
@@ -108,17 +104,13 @@
     d = fromWeekCalendar wt ws y wy dw
     in if toWeekCalendar wt ws d == (y,wy,dw) then Just d else Nothing
 
-#if __GLASGOW_HASKELL__ >= 710
 -- | Bidirectional abstract constructor for ISO 8601 Week Date format.
 -- Invalid week values will be clipped to the correct range.
 pattern YearWeekDay :: Year -> WeekOfYear -> DayOfWeek -> Day
 pattern YearWeekDay y wy dw <- (toWeekDate -> (y,wy,toEnum -> dw)) where
     YearWeekDay y wy dw = fromWeekDate y wy (fromEnum dw)
 
-#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE YearWeekDay #-}
-#endif
-#endif
 
 #endif
 
@@ -178,11 +170,7 @@
 toSomeDay :: DayOfWeek -> Day
 toSomeDay d = ModifiedJulianDay (fromIntegral $ fromEnum d + 4)
 
-#if MIN_VERSION_time(1,8,0)
 #define FORMAT_OPTS tl mpo i
-#else
-#define FORMAT_OPTS tl mpo
-#endif
 
 instance FormatTime DayOfWeek where
     formatCharacter 'u' = fmap (\f FORMAT_OPTS d -> f FORMAT_OPTS (toSomeDay d)) (formatCharacter 'u')
diff --git a/src/Data/Time/Clock/Compat.hs b/src/Data/Time/Clock/Compat.hs
--- a/src/Data/Time/Clock/Compat.hs
+++ b/src/Data/Time/Clock/Compat.hs
@@ -50,21 +50,3 @@
 nominalDiffTimeToSeconds = realToFrac
 
 #endif
-
-#if !MIN_VERSION_time(1,8,0)
--- | One day in 'NominalDiffTime'.
-nominalDay :: NominalDiffTime
-nominalDay = 86400
-#endif
-
-#if !MIN_VERSION_time(1,8,0)
--- | The resolution of 'getSystemTime', 'getCurrentTime', 'getPOSIXTime'
-getTime_resolution :: DiffTime
-getTime_resolution = 1E-6 -- microsecond
-#endif
-
-#if !MIN_VERSION_time(1,6,0)
--- | Get the number of picoseconds in a 'DiffTime'.
-diffTimeToPicoseconds :: DiffTime -> Integer
-diffTimeToPicoseconds = truncate . (1000000000000 *)
-#endif
diff --git a/src/Data/Time/Clock/POSIX/Compat.hs b/src/Data/Time/Clock/POSIX/Compat.hs
--- a/src/Data/Time/Clock/POSIX/Compat.hs
+++ b/src/Data/Time/Clock/POSIX/Compat.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 module Data.Time.Clock.POSIX.Compat (
     posixDayLength,POSIXTime,posixSecondsToUTCTime,utcTimeToPOSIXSeconds,getPOSIXTime,getCurrentTime,
     systemToPOSIXTime,
@@ -9,8 +8,3 @@
 import Data.Time
 import Data.Time.Clock.POSIX
 import Data.Time.Clock.System.Compat
-
-#if !MIN_VERSION_time(1,8,0)
-systemToPOSIXTime :: SystemTime -> POSIXTime
-systemToPOSIXTime (MkSystemTime s ns) = (fromIntegral s) + (fromIntegral ns) * 1E-9
-#endif
diff --git a/src/Data/Time/Clock/System/Compat.hs b/src/Data/Time/Clock/System/Compat.hs
--- a/src/Data/Time/Clock/System/Compat.hs
+++ b/src/Data/Time/Clock/System/Compat.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE DeriveDataTypeable #-}
 module Data.Time.Clock.System.Compat (
     systemEpochDay,
@@ -11,103 +10,4 @@
     ) where
 
 import Data.Time.Orphans ()
-
-#if MIN_VERSION_time(1,8,0)
 import Data.Time.Clock.System
-#else
-
-import Control.DeepSeq (NFData (..))
-import Data.Int (Int64)
-import Data.Word (Word32)
-import Data.Typeable (Typeable)
-import Data.Data (Data)
-
-import Data.Time.Clock.TAI.Compat
-import Data.Time.Clock.POSIX
-import Data.Time.Compat
-
--- | 'SystemTime' is time returned by system clock functions.
--- Its semantics depends on the clock function, but the epoch is typically the beginning of 1970.
--- Note that 'systemNanoseconds' of 1E9 to 2E9-1 can be used to represent leap seconds.
-data SystemTime = MkSystemTime
-    { systemSeconds ::     {-# UNPACK #-} !Int64
-    , systemNanoseconds :: {-# UNPACK #-} !Word32
-    } deriving (Eq,Ord,Show,Typeable,Data)
-
-instance NFData SystemTime where
-    rnf a = a `seq` ()
-
--- | Get the system time, epoch start of 1970 UTC, leap-seconds ignored.
--- 'getSystemTime' is typically much faster than 'getCurrentTime'.
-getSystemTime :: IO SystemTime
-
-
--- Use gettimeofday
-getSystemTime = do
-    t <- getPOSIXTime
-    let secs = truncate t
-    let nsecs = truncate $ 1000000000 * (t - fromIntegral secs)
-    return (MkSystemTime secs nsecs)
-
--- | Map leap-second values to the start of the following second.
--- The resulting 'systemNanoseconds' will always be in the range 0 to 1E9-1.
-truncateSystemTimeLeapSecond :: SystemTime -> SystemTime
-truncateSystemTimeLeapSecond (MkSystemTime seconds nanoseconds) | nanoseconds >= 1000000000 = MkSystemTime (succ seconds) 0
-truncateSystemTimeLeapSecond t = t
-
--- | Convert 'SystemTime' to 'UTCTime', matching zero 'SystemTime' to midnight of 'systemEpochDay' UTC.
-systemToUTCTime :: SystemTime -> UTCTime
-systemToUTCTime (MkSystemTime seconds nanoseconds) = let
-    days :: Int64
-    timeSeconds :: Int64
-    (days, timeSeconds) = seconds `divMod` 86400
-
-    day :: Day
-    day = addDays (fromIntegral days) systemEpochDay
-
-    timeNanoseconds :: Int64
-    timeNanoseconds = timeSeconds * 1000000000 + (fromIntegral nanoseconds)
-
-    timePicoseconds :: Int64
-    timePicoseconds = timeNanoseconds * 1000
-
-    time :: DiffTime
-    time = picosecondsToDiffTime $ fromIntegral timePicoseconds
-    in UTCTime day time
-
--- | Convert 'UTCTime' to 'SystemTime', matching zero 'SystemTime' to midnight of 'systemEpochDay' UTC.
-utcToSystemTime :: UTCTime -> SystemTime
-utcToSystemTime (UTCTime day time) = let
-    days :: Int64
-    days = fromIntegral $ diffDays day systemEpochDay
-
-    timePicoseconds :: Int64
-    timePicoseconds = fromIntegral $ diffTimeToPicoseconds time
-
-    timeNanoseconds :: Int64
-    timeNanoseconds = timePicoseconds `div` 1000
-
-    timeSeconds :: Int64
-    nanoseconds :: Int64
-    (timeSeconds,nanoseconds) = if timeNanoseconds >= 86400000000000 then (86399,timeNanoseconds - 86399000000000) else timeNanoseconds `divMod` 1000000000
-
-    seconds :: Int64
-    seconds = days * 86400 + timeSeconds
-
-    in MkSystemTime seconds $ fromIntegral nanoseconds
-
-systemEpochAbsolute :: AbsoluteTime
-systemEpochAbsolute = taiNominalDayStart systemEpochDay
-
--- | Convert 'SystemTime' to 'AbsoluteTime', matching zero 'SystemTime' to midnight of 'systemEpochDay' TAI.
-systemToTAITime :: SystemTime -> AbsoluteTime
-systemToTAITime (MkSystemTime s ns) = let
-    diff :: DiffTime
-    diff = (fromIntegral s) + (fromIntegral ns) * 1E-9
-    in addAbsoluteTime diff systemEpochAbsolute
-
--- | The day of the epoch of 'SystemTime', 1970-01-01
-systemEpochDay :: Day
-systemEpochDay = ModifiedJulianDay 40587
-
-#endif
diff --git a/src/Data/Time/Clock/TAI/Compat.hs b/src/Data/Time/Clock/TAI/Compat.hs
--- a/src/Data/Time/Clock/TAI/Compat.hs
+++ b/src/Data/Time/Clock/TAI/Compat.hs
@@ -8,12 +8,7 @@
     LeapSecondMap,
 
     -- * conversion between UTC and TAI with map
-#if MIN_VERSION_time(1,7,0)
     T.utcDayLength,T.utcToTAITime,T.taiToUTCTime,
-#else
-    utcDayLength,utcToTAITime,taiToUTCTime,
-#endif
-
     taiClock,
     ) where
 
@@ -22,48 +17,3 @@
 import Data.Time.Compat
 import Data.Time.Clock.TAI hiding (utcDayLength,utcToTAITime,taiToUTCTime)
 import qualified Data.Time.Clock.TAI as T
-
-import Data.Fixed (div')
-
--- | This type is either 'LeapSecondMap' or 'LeapSecondTable', depending
--- on the version of @time@ (changed in @time-1.7.0@).
-#if !(MIN_VERSION_time(1,7,0))
-type LeapSecondMap = Day -> Maybe Int
-
-utcDayLength :: LeapSecondMap -> Day -> Maybe DiffTime
-utcDayLength lsmap day = do
-    i0 <- lsmap day
-    i1 <- lsmap $ addDays 1 day
-    return $ realToFrac (86400 + i1 - i0)
-
-dayStart :: LeapSecondMap -> Day -> Maybe AbsoluteTime
-dayStart lsmap day = do
-    i <- lsmap day
-    return $ addAbsoluteTime (realToFrac $ (toModifiedJulianDay day) * 86400 + toInteger i) taiEpoch
-
-utcToTAITime :: LeapSecondMap -> UTCTime -> Maybe AbsoluteTime
-utcToTAITime lsmap (UTCTime day dtime) = do
-    t <- dayStart lsmap day
-    return $ addAbsoluteTime dtime t
-
-taiToUTCTime :: LeapSecondMap -> AbsoluteTime -> Maybe UTCTime
-taiToUTCTime lsmap abstime = let
-    stable day = do
-        dayt <- dayStart lsmap day
-        len <- utcDayLength lsmap day
-        let
-            dtime = diffAbsoluteTime abstime dayt
-            day' = addDays (div' dtime len) day
-        if day == day' then return (UTCTime day dtime) else stable day'
-    in stable $ ModifiedJulianDay $ div' (diffAbsoluteTime abstime taiEpoch) 86400
-#endif
-
-#if !(MIN_VERSION_time(1,8,0))
-taiNominalDayStart :: Day -> AbsoluteTime
-taiNominalDayStart (ModifiedJulianDay ds) =
-   addAbsoluteTime (secondsToDiffTime (ds * 86400)) taiEpoch
-
--- | TAI clock, if it exists. Note that it is unlikely to be set correctly, without due care and attention.
-taiClock :: Maybe (DiffTime,IO AbsoluteTime)
-taiClock = Nothing
-#endif
diff --git a/src/Data/Time/Format/Compat.hs b/src/Data/Time/Format/Compat.hs
--- a/src/Data/Time/Format/Compat.hs
+++ b/src/Data/Time/Format/Compat.hs
@@ -23,64 +23,17 @@
 
 import Data.Time.Orphans ()
 
-#if !MIN_VERSION_time(1,5,0)
-import Data.Time.Format
-import System.Locale (TimeLocale, defaultTimeLocale, iso8601DateFormat, rfc822DateFormat)
-import Text.ParserCombinators.ReadP (readP_to_S, readS_to_P, ReadP)
-#else
-#if !(MIN_VERSION_time(1,9,0)) || !(MIN_VERSION_base(4,9,0))
+#if !(MIN_VERSION_time(1,9,0))
 import Data.Time.Format hiding (parseTimeM)
 #else
 import Data.Time.Format
 #endif
-#endif
 
 import qualified Control.Monad.Fail as Fail
 import qualified Data.Time.Format
 
-#if !MIN_VERSION_time(1,5,0)
-parseTimeM
-    :: (Fail.MonadFail m, ParseTime t)
-    => Bool       -- ^ Accept leading and trailing whitespace?
-    -> TimeLocale -- ^ Time locale.
-    -> String     -- ^ Format string.
-    -> String     -- ^ Input string.
-    -> m t        -- ^ Return the time value, or fail if the in
-parseTimeM _acceptWS l fmt s = case parseTime l fmt s of
-    Just x  -> return x
-    Nothing -> Fail.fail "parseTimeM: no parse"
-
-parseTimeOrError
-    :: ParseTime t
-    => Bool       -- ^ Accept leading and trailing whitespace?
-    -> TimeLocale -- ^ Time locale.
-    -> String     -- ^ Format string.
-    -> String     -- ^ Input string.
-    -> t          -- ^ The time value.
-parseTimeOrError _acceptWS l fmt s = case parseTime l fmt s of
-    Just x  -> x
-    Nothing -> error "parseTimeOrError: no parse"
-
--- | Parse a time value given a format string.  See 'parseTimeM' for details.
-readSTime :: ParseTime t =>
-             Bool       -- ^ Accept leading whitespace?
-          -> TimeLocale -- ^ Time locale.
-          -> String     -- ^ Format string
-          -> ReadS t
-readSTime _acceptWS l f  = readsTime l f
-
--- | Parse a time value given a format string.  See 'parseTimeM' for details.
-readPTime :: ParseTime t =>
-             Bool       -- ^ Accept leading whitespace?
-          -> TimeLocale -- ^ Time locale.
-          -> String     -- ^ Format string
-          -> ReadP t
-readPTime acceptWS l f = readS_to_P (readSTime acceptWS l f)
-
-#else
-
 -- parseTimeM has always Fail.MonadFail constraint
-#if !MIN_VERSION_time(1,9,0) || !MIN_VERSION_base(4,9,0)
+#if !MIN_VERSION_time(1,9,0)
 -- | Parses a time value given a format string.
 --
 -- This variant from @time-compat@ has always 'Fail.MonadFail' constraint.
@@ -94,7 +47,6 @@
     -> String     -- ^ Input string.
     -> m t        -- ^ Return the time value, or fail if the in
 parseTimeM = Data.Time.Format.parseTimeM
-#endif
 #endif
 
 #if MIN_VERSION_time(1,10,0)
diff --git a/src/Data/Time/Format/ISO8601/Compat.hs b/src/Data/Time/Format/ISO8601/Compat.hs
--- a/src/Data/Time/Format/ISO8601/Compat.hs
+++ b/src/Data/Time/Format/ISO8601/Compat.hs
@@ -80,11 +80,7 @@
 
 -- | Parse a value in either extended or basic format
 parseFormatExtension :: (
-#if MIN_VERSION_base(4,9,0)
     MonadFail m
-#else
-    Monad m
-#endif
     ) => (FormatExtension -> Format t) -> String -> m t
 parseFormatExtension ff = parseReader $ formatReadPExtension ff
 
@@ -357,11 +353,7 @@
 
 -- | Parse the most commonly used ISO 8601 format.
 iso8601ParseM :: (
-#if MIN_VERSION_base(4,9,0)
     MonadFail m
-#else
-    Monad m
-#endif
     ,ISO8601 t) => String -> m t
 iso8601ParseM = formatParseM iso8601Format
 
diff --git a/src/Data/Time/Orphans.hs b/src/Data/Time/Orphans.hs
--- a/src/Data/Time/Orphans.hs
+++ b/src/Data/Time/Orphans.hs
@@ -15,15 +15,8 @@
 import Data.Time.Format
 import Data.Hashable (Hashable (..))
 
-#if MIN_VERSION_time(1,5,0)
 import Data.Time.Format (TimeLocale (..))
-#else
-import System.Locale (TimeLocale (..))
-#endif
-
-#if MIN_VERSION_time(1,8,0)
 import Data.Time.Clock.System
-#endif
 
 #if !MIN_VERSION_time(1,11,0)
 import Data.Fixed (Pico)
@@ -38,39 +31,15 @@
 import Data.Time.Calendar.Quarter
 #endif
 
-#if !MIN_VERSION_time(1,6,0)
-instance ParseTime UniversalTime where
-    -- substituteTimeSpecifier _ = timeSubstituteTimeSpecifier
-    -- parseTimeSpecifier _ = timeParseTimeSpecifier
-    buildTime l xs = localTimeToUT1 0 (buildTime l xs)
-
-instance FormatTime UniversalTime where
-    formatCharacter c = fmap (\f tl fo t -> f tl fo (ut1ToLocalTime 0 t)) (formatCharacter c)
-
-instance Show UniversalTime where
-    show t = show (ut1ToLocalTime 0 t)
-
-instance Read UniversalTime where
-    readsPrec n s = [ (localTimeToUT1 0 t, r) | (t,r) <- readsPrec n s ]
-#endif
-
-
 #if MIN_VERSION_time(1,9,0) && !MIN_VERSION_time(1,11,0)
 deriving instance Ord DayOfWeek
 #endif
 
 #if MIN_VERSION_time(1,9,0) && !MIN_VERSION_time(1,10,0)
-#if __GLASGOW_HASKELL__ <710
-deriving instance Typeable DayOfWeek
-#endif
 deriving instance Data DayOfWeek
 #endif
 
 #if MIN_VERSION_time(1,8,0) && !MIN_VERSION_time(1,10,0)
-#if __GLASGOW_HASKELL__ <710
-deriving instance Typeable SystemTime
-#endif
-
 deriving instance Data SystemTime
 #endif
 
diff --git a/test/main/Test/Calendar/CalendarProps.hs b/test/main/Test/Calendar/CalendarProps.hs
--- a/test/main/Test/Calendar/CalendarProps.hs
+++ b/test/main/Test/Calendar/CalendarProps.hs
@@ -3,7 +3,6 @@
     ( testCalendarProps
     ) where
 
-#if __GLASGOW_HASKELL__ >= 710
 import Data.Time.Calendar.Month.Compat
 import Data.Time.Calendar.Quarter.Compat
 import Test.TestUtil
@@ -24,11 +23,3 @@
 
 testCalendarProps :: TestTree
 testCalendarProps = nameTest "calender-props" [testYearMonth,testMonthDay,testYearQuarter]
-#else
-
-import Test.Tasty
-
-testCalendarProps :: TestTree
-testCalendarProps = testGroup "calendar-props" []
-
-#endif
diff --git a/test/main/Test/Clock/Resolution.hs b/test/main/Test/Clock/Resolution.hs
--- a/test/main/Test/Clock/Resolution.hs
+++ b/test/main/Test/Clock/Resolution.hs
@@ -25,7 +25,7 @@
 gcdAll = foldr gcd' 0
 
 testResolution :: (Show dt, Real dt) => String -> (at -> at -> dt) -> (dt, IO at) -> TestTree
-testResolution name timeDiff (res, getTime) =
+testResolution name timeDiff (reportedRes, getTime) =
     testCase name $ do
         t0 <- getTime
         times0 <-
@@ -53,11 +53,8 @@
                 threadDelay 1000 -- 1ms
                 getTime
         let times = fmap (\t -> timeDiff t t0) $ times0 ++ times1 ++ times2 ++ times3 ++ times4
-#if MIN_VERSION_time(1,8,0)
-        assertEqual "resolution" res $ gcdAll times
-#else
-        assertBool ("resolution " ++ show (res, gcdAll times)) (res >= gcdAll times)
-#endif
+            foundGrid = gcdAll times
+        assertBool ("resolution " ++ show (reportedRes, foundGrid)) (foundGrid <= reportedRes)
 
 testResolutions :: TestTree
 testResolutions =
diff --git a/test/main/Test/Format/ParseTime.hs b/test/main/Test/Format/ParseTime.hs
--- a/test/main/Test/Format/ParseTime.hs
+++ b/test/main/Test/Format/ParseTime.hs
@@ -5,10 +5,6 @@
     , test_parse_format
     ) where
 
-#if MIN_VERSION_base(4,11,0)
-#else
-import Data.Semigroup hiding (option)
-#endif
 import Control.Monad
 import Data.Char
 import Data.Maybe
@@ -24,7 +20,7 @@
 import Test.Tasty.HUnit
 import Test.Tasty.QuickCheck hiding (reason)
 import Test.TestUtil
-import Text.Read.Compat
+import Text.Read
 
 format :: FormatTime t => String -> t -> String
 format f t = formatTime defaultTimeLocale f t
diff --git a/time-compat.cabal b/time-compat.cabal
--- a/time-compat.cabal
+++ b/time-compat.cabal
@@ -1,6 +1,6 @@
 cabal-version:      1.12
 name:               time-compat
-version:            1.9.6.1
+version:            1.9.7
 synopsis:           Compatibility package for time
 description:
   This packages tries to compat as much of @time@ features as possible.
@@ -23,54 +23,31 @@
 build-type:         Simple
 extra-source-files: CHANGELOG.md
 tested-with:
-  GHC ==7.4.2
-   || ==7.6.3
-   || ==7.8.4
-   || ==7.10.3
-   || ==8.0.2
-   || ==8.2.2
-   || ==8.4.4
-   || ==8.6.5
+  GHC ==8.6.5
    || ==8.8.4
-   || ==8.10.4
-   || ==9.0.1
+   || ==8.10.7
+   || ==9.0.2
+   || ==9.2.8
+   || ==9.4.8
+   || ==9.6.5
+   || ==9.8.2
+   || ==9.10.1
 
 source-repository head
   type:     git
   location: https://github.com/haskellari/time-compat.git
 
-flag old-locale
-  description: If true, use old-locale, otherwise use time 1.5 or newer.
-  manual:      False
-  default:     False
-
 library
-  default-language: Haskell2010
-  hs-source-dirs:   src
-  other-extensions: CPP
-
-  if impl(ghc >=7.2)
-    default-extensions: Trustworthy
-
+  default-language:   Haskell2010
+  hs-source-dirs:     src
+  other-extensions:   CPP
+  default-extensions: Trustworthy
   build-depends:
-      base          >=4.5     && <4.16
-    , base-orphans  >=0.8.4   && <0.9
-    , deepseq       >=1.3.0.0 && <1.4 || >=1.4.1.1 && <1.5
-    , time          >=1.4     && <1.7 || >=1.8 && <1.9 || >=1.9.2 && <1.9.4 || >=1.10 && <1.10.1 || >=1.11 && <1.11.2 || >=1.12 && <1.13
-    , hashable      >=1.3.2.0 && <1.4
-
-  if flag(old-locale)
-    build-depends:
-        old-locale  >=1.0.0.2 && <1.1
-      , time        >=1.4     && <1.5
-
-  else
-    build-depends: time >=1.5
-
-  if !impl(ghc >=8.0)
-    build-depends:
-        fail        >=4.9.0.0 && <4.10
-      , semigroups  >=0.18.5  && <0.20
+      base          >=4.12    && <4.21
+    , base-orphans  >=0.9.2   && <0.10
+    , deepseq       >=1.4.4.0 && <1.6
+    , hashable      >=1.4.4.0 && <1.5
+    , time          >=1.8.0.2 && <1.9  || >=1.9.2 && <1.9.4 || >=1.10 && <1.10.1 || >=1.11 && <1.11.2 || >=1.12 && <1.13
 
   exposed-modules:
     Data.Time.Calendar.Compat
@@ -104,8 +81,8 @@
   build-depends:
       base
     , deepseq
-    , HUnit        >=1.3.1 && <1.3.2 || >=1.6.0.0 && <1.7
-    , hashable     >=1.3.1.0 && <1.4
+    , hashable     >=1.4.0.0 && <1.5
+    , HUnit        >=1.3.1   && <1.3.2 || >=1.6.0.0 && <1.7
     , time-compat
 
 -- This test-suite is from time library
@@ -138,11 +115,10 @@
   ghc-options:        -Wall -fwarn-tabs
   build-depends:
       base
-    , base-compat       >=0.10.5 && <0.12
     , deepseq
-    , QuickCheck        >=2.13   && <2.15
+    , QuickCheck        >=2.13   && <2.16
     , tagged            >=0.8.6  && <0.9
-    , tasty             >=1.2.1  && <1.5
+    , tasty             >=1.5    && <1.6
     , tasty-hunit       >=0.10   && <0.11
     , tasty-quickcheck  >=0.10   && <0.11
     , time-compat
@@ -150,7 +126,7 @@
   if !impl(ghc >=8.0)
     build-depends:
         fail        >=4.9.0.0 && <4.10
-      , semigroups  >=0.18.5  && <0.20
+      , semigroups  >=0.18.5  && <0.21
 
   build-depends:      time
   main-is:            Main.hs