diff --git a/src/Data/Thyme/Format.hs b/src/Data/Thyme/Format.hs
index 03eda64..e904c32 100644
--- a/src/Data/Thyme/Format.hs
+++ b/src/Data/Thyme/Format.hs
@@ -27,6 +27,7 @@ import Data.Bits
 import qualified Data.ByteString.Char8 as S
 import Data.Char
 import Data.Micro
+import Data.Int
 import Data.Thyme.Calendar
 import Data.Thyme.Calendar.Internal
 import Data.Thyme.Calendar.MonthDay
@@ -358,7 +359,7 @@ timeParser TimeLocale {..} = flip execStateT unixEpoch . go where
             -- UTCTime
             's' -> do
                 s <- lift (negative P.decimal)
-                _tpPOSIXTime .= fromSeconds (s :: Int)
+                _tpPOSIXTime .= fromSeconds (s :: Int64)
                 flag IsPOSIXTime .= True
                 go rspec
 
diff --git a/tests/Common.hs b/tests/Common.hs
index 97e331e..60275b2 100644
--- a/tests/Common.hs
+++ b/tests/Common.hs
@@ -4,6 +4,7 @@ module Common where
 import Prelude
 import Control.Applicative
 import Control.Lens
+import Data.Int
 import Data.Thyme
 import System.Exit
 import Test.QuickCheck
@@ -15,7 +16,8 @@ exit b = exitWith $ if b then ExitSuccess else ExitFailure 1
 ------------------------------------------------------------------------
 
 instance Arbitrary Day where
-    arbitrary = ModifiedJulianDay <$> arbitrary
+    -- To avoid overflows in Day --> YearMonthDay conversion on 32 bit platforms:
+    arbitrary = ModifiedJulianDay <$> (fromIntegral :: Int -> Int64) <$> arbitrary
 
 instance Arbitrary DiffTime where
     arbitrary = view microDiffTime <$> arbitrary