diff --git a/src/Data/Thyme/Calendar/Internal.hs b/src/Data/Thyme/Calendar/Internal.hs
--- a/src/Data/Thyme/Calendar/Internal.hs
+++ b/src/Data/Thyme/Calendar/Internal.hs
@@ -22,12 +22,12 @@
 import Control.Lens
 import Control.Monad
 import Data.AffineSpace
-import Data.Bits ((.&.))
+import Data.Bits
 import Data.Data
 import Data.Int
 import Data.Ix
 import Data.Thyme.Format.Internal
-#if __GLASGOW_HASKELL__ != 706
+#if __GLASGOW_HASKELL__ == 704
 import qualified Data.Vector.Generic
 import qualified Data.Vector.Generic.Mutable
 #endif
@@ -407,27 +407,27 @@
 derivingUnbox "Day" [t| Day -> Int |]
     [| toModifiedJulianDay |] [| ModifiedJulianDay |]
 
-derivingUnbox "YearMonthDay" [t| YearMonthDay -> (Year, Month, DayOfMonth) |]
-    [| \ YearMonthDay {..} -> (ymdYear, ymdMonth, ymdDay) |]
-    [| \ (ymdYear, ymdMonth, ymdDay) -> YearMonthDay {..} |]
+derivingUnbox "YearMonthDay" [t| YearMonthDay -> Int |]
+    [| \ YearMonthDay {..} -> shiftL ymdYear 9 .|. shiftL ymdMonth 5 .|. ymdDay |]
+    [| \ n -> YearMonthDay (shiftR n 9) (shiftR n 5 .&. 0xf) (n .&. 0x1f) |]
 
-derivingUnbox "OrdinalDate" [t| OrdinalDate -> (Year, DayOfYear) |]
-    [| \ OrdinalDate {..} -> (odYear, odDay) |]
-    [| \ (odYear, odDay) -> OrdinalDate {..} |]
+derivingUnbox "OrdinalDate" [t| OrdinalDate -> Int |]
+    [| \ OrdinalDate {..} -> shiftL odYear 9 .|. odDay |]
+    [| \ n -> OrdinalDate (shiftR n 9) (n .&. 0x1ff) |]
 
-derivingUnbox "MonthDay" [t| MonthDay -> (Month, DayOfMonth) |]
-    [| \ MonthDay {..} -> (mdMonth, mdDay) |]
-    [| \ (mdMonth, mdDay) -> MonthDay {..} |]
+derivingUnbox "MonthDay" [t| MonthDay -> Int |]
+    [| \ MonthDay {..} -> shiftL mdMonth 5 .|. mdDay |]
+    [| \ n -> MonthDay (shiftR n 5) (n .&. 0x1f) |]
 
-derivingUnbox "WeekDate" [t| WeekDate -> (Year, WeekOfYear, DayOfWeek) |]
-    [| \ WeekDate {..} -> (wdYear, wdWeek, wdDay) |]
-    [| \ (wdYear, wdWeek, wdDay) -> WeekDate {..} |]
+derivingUnbox "WeekDate" [t| WeekDate -> Int |]
+    [| \ WeekDate {..} -> shiftL wdYear 9 .|. shiftL wdWeek 3 .|. wdDay |]
+    [| \ n -> WeekDate (shiftR n 9) (shiftR n 3 .&. 0x3f) (n .&. 0x7) |]
 
-derivingUnbox "SundayWeek" [t| SundayWeek -> (Year, WeekOfYear, DayOfWeek) |]
-    [| \ SundayWeek {..} -> (swYear, swWeek, swDay) |]
-    [| \ (swYear, swWeek, swDay) -> SundayWeek {..} |]
+derivingUnbox "SundayWeek" [t| SundayWeek -> Int |]
+    [| \ SundayWeek {..} -> shiftL swYear 9 .|. shiftL swWeek 3 .|. swDay |]
+    [| \ n -> SundayWeek (shiftR n 9) (shiftR n 3 .&. 0x3f) (n .&. 0x7) |]
 
-derivingUnbox "MondayWeek" [t| MondayWeek -> (Year, WeekOfYear, DayOfWeek) |]
-    [| \ MondayWeek {..} -> (mwYear, mwWeek, mwDay) |]
-    [| \ (mwYear, mwWeek, mwDay) -> MondayWeek {..} |]
+derivingUnbox "MondayWeek" [t| MondayWeek -> Int |]
+    [| \ MondayWeek {..} -> shiftL mwYear 9 .|. shiftL mwWeek 3 .|. mwDay |]
+    [| \ n -> MondayWeek (shiftR n 9) (shiftR n 3 .&. 0x3f) (n .&. 0x7) |]
 
diff --git a/src/Data/Thyme/Calendar/WeekdayOfMonth.hs b/src/Data/Thyme/Calendar/WeekdayOfMonth.hs
--- a/src/Data/Thyme/Calendar/WeekdayOfMonth.hs
+++ b/src/Data/Thyme/Calendar/WeekdayOfMonth.hs
@@ -21,17 +21,18 @@
 import Control.Lens
 import Control.Monad
 import Data.AffineSpace
+import Data.Bits
 import Data.Data
 import Data.Thyme.Calendar
 import Data.Thyme.Calendar.Internal
-#if __GLASGOW_HASKELL__ != 706
+#if __GLASGOW_HASKELL__ == 704
 import qualified Data.Vector.Generic
 import qualified Data.Vector.Generic.Mutable
 #endif
 import Data.Vector.Unboxed.Deriving
 import GHC.Generics (Generic)
 import System.Random
-import Test.QuickCheck
+import Test.QuickCheck hiding ((.&.))
 
 data WeekdayOfMonth = WeekdayOfMonth
     { womYear :: {-# UNPACK #-}!Year
@@ -41,9 +42,11 @@
     } deriving (INSTANCES_USUAL, Show)
 
 derivingUnbox "WeekdayOfMonth"
-    [t| WeekdayOfMonth -> (Year, Month, Int, DayOfWeek) |]
-    [| \ WeekdayOfMonth {..} -> (womYear, womMonth, womNth, womDayOfWeek) |]
-    [| \ (womYear, womMonth, womNth, womDayOfWeek) -> WeekdayOfMonth {..} |]
+    [t| WeekdayOfMonth -> Int |]
+    [| \ WeekdayOfMonth {..} -> shiftL womYear 11 .|. shiftL womMonth 7
+        .|. shiftL (womNth + 5) 3 .|. womDayOfWeek |]
+    [| \ n -> WeekdayOfMonth (shiftR n 11) (shiftR n 7 .&. 0xf)
+        (shiftR n 3 - 5) (n .&. 0x7) |]
 
 instance NFData WeekdayOfMonth
 
diff --git a/src/Data/Thyme/Clock/Internal.hs b/src/Data/Thyme/Clock/Internal.hs
--- a/src/Data/Thyme/Clock/Internal.hs
+++ b/src/Data/Thyme/Clock/Internal.hs
@@ -26,7 +26,7 @@
 import Data.Ix
 import Data.Thyme.Internal.Micro
 import Data.Thyme.Calendar.Internal
-#if __GLASGOW_HASKELL__ != 706
+#if __GLASGOW_HASKELL__ == 704
 import qualified Data.Vector.Generic
 import qualified Data.Vector.Generic.Mutable
 #endif
diff --git a/src/Data/Thyme/Clock/TAI.hs b/src/Data/Thyme/Clock/TAI.hs
--- a/src/Data/Thyme/Clock/TAI.hs
+++ b/src/Data/Thyme/Clock/TAI.hs
@@ -46,7 +46,7 @@
 import Data.Thyme.Clock.Internal
 import Data.Thyme.Format.Internal
 import Data.Thyme.LocalTime
-#if __GLASGOW_HASKELL__ != 706
+#if __GLASGOW_HASKELL__ == 704
 import qualified Data.Vector.Generic
 import qualified Data.Vector.Generic.Mutable
 #endif
diff --git a/src/Data/Thyme/Internal/Micro.hs b/src/Data/Thyme/Internal/Micro.hs
--- a/src/Data/Thyme/Internal/Micro.hs
+++ b/src/Data/Thyme/Internal/Micro.hs
@@ -21,7 +21,7 @@
 import Data.Int
 import Data.Ix
 import Data.Ratio
-#if __GLASGOW_HASKELL__ != 706
+#if __GLASGOW_HASKELL__ == 704
 import qualified Data.Vector.Generic
 import qualified Data.Vector.Generic.Mutable
 #endif
diff --git a/src/Data/Thyme/LocalTime.hs b/src/Data/Thyme/LocalTime.hs
--- a/src/Data/Thyme/LocalTime.hs
+++ b/src/Data/Thyme/LocalTime.hs
@@ -22,7 +22,9 @@
 import Control.Lens
 import Control.Monad
 import Data.AffineSpace
+import Data.Bits
 import Data.Data
+import Data.Int
 import Data.Thyme.Internal.Micro
 import Data.Thyme.Calendar
 import Data.Thyme.Calendar.Internal
@@ -30,7 +32,7 @@
 import Data.Thyme.Clock.Internal
 import Data.Thyme.Format.Internal
 import qualified Data.Time as T
-#if __GLASGOW_HASKELL__ != 706
+#if __GLASGOW_HASKELL__ == 704
 import qualified Data.Vector.Generic
 import qualified Data.Vector.Generic.Mutable
 #endif
@@ -38,7 +40,7 @@
 import Data.VectorSpace
 import GHC.Generics (Generic)
 import System.Random
-import Test.QuickCheck
+import Test.QuickCheck hiding ((.&.))
 
 type Minutes = Int
 type Hours = Int
@@ -129,9 +131,11 @@
     , todSec :: {-# UNPACK #-}!DiffTime
     } deriving (INSTANCES_USUAL)
 
-derivingUnbox "TimeOfDay" [t| TimeOfDay -> (Hour, Minute, DiffTime) |]
-    [| \ TimeOfDay {..} -> (todHour, todMin, todSec) |]
-    [| \ (todHour, todMin, todSec) -> TimeOfDay {..} |]
+derivingUnbox "TimeOfDay" [t| TimeOfDay -> Int64 |]
+    [| \ TimeOfDay {..} -> fromIntegral (todHour .|. shiftL todMin 8)
+        .|. shiftL (todSec ^. microseconds) 16 |]
+    [| \ n -> TimeOfDay (fromIntegral $ n .&. 0xff)
+        (fromIntegral $ shiftR n 8 .&. 0xff) (microseconds # shiftR n 16) |]
 
 instance NFData TimeOfDay
 
diff --git a/thyme.cabal b/thyme.cabal
--- a/thyme.cabal
+++ b/thyme.cabal
@@ -1,5 +1,5 @@
 name:           thyme
-version:        0.3.5.0
+version:        0.3.5.1
 synopsis:       A faster time library
 description:
     Thyme is a rewrite of the fine @time@ library, with a particular focus
@@ -92,7 +92,7 @@
         text >= 0.11,
         time >= 1.4,
         vector >= 0.9,
-        vector-th-unbox >= 0.2,
+        vector-th-unbox >= 0.2.1.0,
         vector-space >= 0.8
     if os(windows)
         build-depends: Win32