diff --git a/nanotime.cabal b/nanotime.cabal
--- a/nanotime.cabal
+++ b/nanotime.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           nanotime
-version:        0.3.1
+version:        0.3.2
 synopsis:       a tiny time library
 description:    Please see the README on GitHub at <https://github.com/ejconlon/nanotime#readme>
 homepage:       https://github.com/ejconlon/nanotime#readme
diff --git a/src/Nanotime.hs b/src/Nanotime.hs
--- a/src/Nanotime.hs
+++ b/src/Nanotime.hs
@@ -177,7 +177,8 @@
   target <$ threadDelayDelta td
 
 newtype PosixTime = PosixTime {unPosixTime :: Word64}
-  deriving stock (Eq, Show, Ord, Bounded)
+  deriving stock (Show)
+  deriving newtype (Eq, Ord, Bounded, Num)
 
 -- | Show 'PosixTime' as a UTC ISO-8601 String for debugging
 showPosixTime :: PosixTime -> String
@@ -199,7 +200,8 @@
 
 -- | Monotonic time in nanoseconds since some unspecified epoch (see 'getMonotonicTimeNs')
 newtype MonoTime = MonoTime {unMonoTime :: Word64}
-  deriving stock (Eq, Show, Ord, Bounded)
+  deriving stock (Show)
+  deriving newtype (Eq, Ord, Bounded, Num)
 
 monoTimeFromFracSecs :: (Real a, Show a) => a -> MonoTime
 monoTimeFromFracSecs d = MonoTime (round (1000000000 * toRational (assertingNonNegative d)))
@@ -219,7 +221,8 @@
   currentTime = fmap MonoTime getMonotonicTimeNSec
 
 newtype NtpTime = NtpTime {unNtpTime :: Word64}
-  deriving stock (Eq, Show, Ord, Bounded)
+  deriving stock (Show)
+  deriving newtype (Eq, Ord, Bounded, Num)
 
 -- private
 nanoWordToSplit :: Word64 -> (Word32, Word32)