diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,10 @@
 # ChangeLog for unix-time
 
+## v0.5.0
+
+* Remove deprecated `old-time` dependency by dropping `fromClockTime` and `toClockTime`
+  [#68](https://github.com/kazu-yamamoto/unix-time/pull/68)
+
 ## v0.4.17
 
 * Fix MinGW64 linker error
diff --git a/Data/UnixTime.hs b/Data/UnixTime.hs
--- a/Data/UnixTime.hs
+++ b/Data/UnixTime.hs
@@ -25,9 +25,7 @@
 
     -- * Translating time
     fromEpochTime,
-    toEpochTime,
-    fromClockTime,
-    toClockTime,
+    toEpochTime
 ) where
 
 import Data.UnixTime.Conv
diff --git a/Data/UnixTime/Conv.hs b/Data/UnixTime/Conv.hs
--- a/Data/UnixTime/Conv.hs
+++ b/Data/UnixTime/Conv.hs
@@ -9,9 +9,7 @@
     webDateFormat,
     mailDateFormat,
     fromEpochTime,
-    toEpochTime,
-    fromClockTime,
-    toClockTime,
+    toEpochTime
 ) where
 
 import Control.Applicative
@@ -23,7 +21,6 @@
 import Foreign.Marshal.Alloc
 import System.IO.Unsafe (unsafePerformIO)
 import System.Posix.Types (EpochTime)
-import System.Time (ClockTime (..))
 
 -- $setup
 -- >>> import Data.Function (on)
@@ -143,19 +140,3 @@
 -- From 'UnixTime' to 'EpochTime' ignoring 'utMicroSeconds'.
 toEpochTime :: UnixTime -> EpochTime
 toEpochTime (UnixTime sec _) = sec
-
--- |
--- From 'ClockTime' to 'UnixTime'.
-fromClockTime :: ClockTime -> UnixTime
-fromClockTime (TOD sec psec) = UnixTime sec' usec'
-  where
-    sec' = fromIntegral sec
-    usec' = fromIntegral $ psec `div` 1000000
-
--- |
--- From 'UnixTime' to 'ClockTime'.
-toClockTime :: UnixTime -> ClockTime
-toClockTime (UnixTime sec usec) = TOD sec' psec'
-  where
-    sec' = truncate (toRational sec)
-    psec' = fromIntegral $ usec * 1000000
diff --git a/unix-time.cabal b/unix-time.cabal
--- a/unix-time.cabal
+++ b/unix-time.cabal
@@ -1,6 +1,6 @@
 cabal-version:      1.18
 name:               unix-time
-version:            0.4.17
+version:            0.5.0
 license:            BSD3
 license-file:       LICENSE
 maintainer:         Kazu Yamamoto <kazu@iij.ad.jp>
@@ -47,7 +47,6 @@
     build-depends:
         base >=4.4 && <5,
         bytestring,
-        old-time,
         binary
 
     if impl(ghc >=7.8)
@@ -74,8 +73,6 @@
     build-depends:
         base,
         bytestring,
-        old-locale,
-        old-time,
         QuickCheck,
         template-haskell,
         time,