diff --git a/src/Data/Validity/Time.hs b/src/Data/Validity/Time.hs
--- a/src/Data/Validity/Time.hs
+++ b/src/Data/Validity/Time.hs
@@ -1,5 +1,5 @@
-{-# OPTIONS_GHC -Wno-orphans #-}
-{-# OPTIONS_GHC -Wno-dodgy-exports #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# OPTIONS_GHC -fno-warn-dodgy-exports #-}
 
 module Data.Validity.Time
     ( module X
diff --git a/src/Data/Validity/Time/Calendar.hs b/src/Data/Validity/Time/Calendar.hs
--- a/src/Data/Validity/Time/Calendar.hs
+++ b/src/Data/Validity/Time/Calendar.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS_GHC -Wno-orphans #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
 
 module Data.Validity.Time.Calendar where
 
diff --git a/src/Data/Validity/Time/Clock.hs b/src/Data/Validity/Time/Clock.hs
--- a/src/Data/Validity/Time/Clock.hs
+++ b/src/Data/Validity/Time/Clock.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS_GHC -Wno-orphans #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# LANGUAGE RecordWildCards #-}
 
 module Data.Validity.Time.Clock where
@@ -12,17 +12,17 @@
 instance Validity UniversalTime where
     isValid (ModJulianDate i) = isValid i
 
--- | Valid according to the validity of the result of 'diffTimeToPicoseconds'
+-- | Trivially valid
 instance Validity DiffTime where
-    isValid = isValid . diffTimeToPicoseconds
+    isValid = const True
 
 instance Validity UTCTime where
     isValid UTCTime {..} =
         and
             [ isValid utctDay
             , isValid utctDayTime
-            , diffTimeToPicoseconds utctDayTime >= 0
-            , diffTimeToPicoseconds utctDayTime < 86401 * 10 ^ (12 :: Integer)
+            , utctDayTime >= 0
+            , utctDayTime < 86401
             ]
 
 instance Validity NominalDiffTime where
diff --git a/src/Data/Validity/Time/Format.hs b/src/Data/Validity/Time/Format.hs
--- a/src/Data/Validity/Time/Format.hs
+++ b/src/Data/Validity/Time/Format.hs
@@ -1,5 +1,6 @@
-{-# OPTIONS_GHC -Wno-orphans #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE CPP #-}
 
 module Data.Validity.Time.Format where
 
@@ -8,7 +9,7 @@
 import Data.Time.Format
 
 import Data.Validity.Time.LocalTime ()
-
+#if MIN_VERSION_time(1,5,0)
 -- | Valid according to the contained values
 instance Validity TimeLocale where
     isValid TimeLocale {..} =
@@ -22,3 +23,4 @@
             , isValid time12Fmt
             , isValid knownTimeZones
             ]
+#endif
diff --git a/src/Data/Validity/Time/LocalTime.hs b/src/Data/Validity/Time/LocalTime.hs
--- a/src/Data/Validity/Time/LocalTime.hs
+++ b/src/Data/Validity/Time/LocalTime.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS_GHC -Wno-orphans #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# LANGUAGE RecordWildCards #-}
 
 module Data.Validity.Time.LocalTime where
diff --git a/validity-time.cabal b/validity-time.cabal
--- a/validity-time.cabal
+++ b/validity-time.cabal
@@ -1,5 +1,5 @@
 name: validity-time
-version: 0.0.0.0
+version: 0.0.0.1
 cabal-version: >=1.10
 build-type: Simple
 license: MIT
@@ -25,7 +25,7 @@
         Data.Validity.Time.Format
         Data.Validity.Time.LocalTime
     build-depends:
-        base <5,
+        base >= 4.7 && <5,
         validity -any,
         time -any
     default-language: Haskell2010