diff --git a/haste-compiler.cabal b/haste-compiler.cabal
--- a/haste-compiler.cabal
+++ b/haste-compiler.cabal
@@ -1,5 +1,5 @@
 Name:           haste-compiler
-Version:        0.5.4.2
+Version:        0.5.5.0
 License:        BSD3
 License-File:   LICENSE
 Synopsis:       Haskell To ECMAScript compiler
@@ -105,7 +105,7 @@
         buildable: False
     Hs-Source-Dirs: src
     Include-Dirs: include
-    GHC-Options: -Wall -O2
+    GHC-Options: -Wall -threaded
     if flag(portable)
         CPP-Options: -DPORTABLE
     if flag(static)
@@ -186,10 +186,10 @@
           if os(linux)
             GHC-Options: -static -optl-static -optl-pthread
 
-    Build-Depends: base       >= 4   && < 5,
-                   directory  >= 1   && < 1.3,
-                   process    >= 1   && < 1.3,
-                   Cabal,
+    Build-Depends: base       >= 4    && < 5,
+                   directory  >= 1    && < 1.3,
+                   process    >= 1    && < 1.3,
+                   Cabal      >= 1.22 && < 1.24,
                    containers,
                    filepath,
                    binary,
diff --git a/lib/Integer.js b/lib/Integer.js
--- a/lib/Integer.js
+++ b/lib/Integer.js
@@ -37,7 +37,7 @@
     return a.div(b);
 }
 var I_divMod = function(a,b) {
-    return {_:0, a:I_div(self, other), b:a.mod(b)};
+    return {_:0, a:I_div(a,b), b:a.mod(b)};
 }
 var I_quot = function(a,b) {return a.div(b);}
 var I_rem = function(a,b) {return a.mod(b);}
diff --git a/lib/pointers.js b/lib/pointers.js
--- a/lib/pointers.js
+++ b/lib/pointers.js
@@ -14,8 +14,19 @@
     addr['v'][type][addr.off/elemsize + off] = x;
 }
 
+function writeOffAddr64(addr, off, x) {
+    addr['v']['w32'][addr.off/8 + off*2] = x.low;
+    addr['v']['w32'][addr.off/8 + off*2 + 1] = x.high;
+}
+
 function readOffAddr(type, elemsize, addr, off) {
     return addr['v'][type][addr.off/elemsize + off];
+}
+
+function readOffAddr64(signed, addr, off) {
+    var w64 = hs_mkWord64( addr['v']['w32'][addr.off/8 + off*2]
+                         , addr['v']['w32'][addr.off/8 + off*2 + 1]);
+    return signed ? hs_word64ToInt64(w64) : w64;
 }
 
 // Two addresses are equal if they point to the same buffer and have the same
diff --git a/libraries/haste-lib/src/Haste/Binary.hs b/libraries/haste-lib/src/Haste/Binary.hs
--- a/libraries/haste-lib/src/Haste/Binary.hs
+++ b/libraries/haste-lib/src/Haste/Binary.hs
@@ -17,6 +17,7 @@
 import Data.Int
 import Data.Word
 import Data.Char
+import GHC.Fingerprint.Type
 import qualified Haste.JSString as J (length)
 import Haste.Prim
 import Haste.Concurrent
@@ -89,6 +90,16 @@
     gput :: f t -> Put
     gget :: Get (f t)
 
+instance Binary Bool where
+  put True = putWord8 1
+  put _    = putWord8 0
+  get = do
+    n <- getWord8
+    case n of
+      0 -> pure False
+      1 -> pure True
+      _ -> fail $ "Not a valid Bool: " ++ show n
+
 instance Binary Word8 where
   put = putWord8
   get = getWord8
@@ -101,6 +112,15 @@
   put = putWord32le
   get = getWord32le
 
+instance Binary Word64 where
+  get = do
+    lo <- get :: Get Word32
+    hi <- get :: Get Word32
+    return $ fromIntegral lo .|. shiftL (fromIntegral hi) 32
+  put x = do
+    put (fromIntegral x :: Word32)
+    put (fromIntegral (shiftR x 32) :: Word32)
+
 instance Binary Int8 where
   put = putInt8
   get = getInt8
@@ -113,6 +133,15 @@
   put = putInt32le
   get = getInt32le
 
+instance Binary Int64 where
+  get = do
+    lo <- get :: Get Int32
+    hi <- get :: Get Int32
+    return $ fromIntegral lo .|. shiftL (fromIntegral hi) 32
+  put x = do
+    put (fromIntegral x :: Int32)
+    put (fromIntegral (shiftR x 32) :: Int32)
+
 instance Binary Int where
   put = putInt32le . fromIntegral
   get = fromIntegral <$> getInt32le
@@ -124,6 +153,10 @@
 instance Binary Double where
   put = putFloat64le
   get = getFloat64le
+
+instance Binary Fingerprint where
+  get = Fingerprint <$> get <*> get
+  put (Fingerprint a b) = put a >> put b
 
 instance (Binary a, Binary b) => Binary (a, b) where
   put (a, b) = put a >> put b
diff --git a/libraries/haste-lib/src/Haste/DOM/JSString.hs b/libraries/haste-lib/src/Haste/DOM/JSString.hs
--- a/libraries/haste-lib/src/Haste/DOM/JSString.hs
+++ b/libraries/haste-lib/src/Haste/DOM/JSString.hs
@@ -57,7 +57,7 @@
 
 jsElemsByClassName :: JSString -> IO [Elem]
 jsElemsByClassName = ffi "(function(c){\
-\return document.getElementsByClassName(e);})"
+\return document.getElementsByClassName(c);})"
 
 jsCreateElem :: JSString -> IO Elem
 jsCreateElem = ffi "(function(t){return document.createElement(t);})"
diff --git a/libraries/haste-lib/src/Haste/JSON.hs b/libraries/haste-lib/src/Haste/JSON.hs
--- a/libraries/haste-lib/src/Haste/JSON.hs
+++ b/libraries/haste-lib/src/Haste/JSON.hs
@@ -66,7 +66,7 @@
   negate _          = numFail
   abs (Num a)       = Num (abs a)
   abs _             = numFail
-  signum (Num a)    = signum (Num a)
+  signum (Num a)    = Num (signum a)
   signum _          = numFail
   fromInteger n     = Num (fromInteger n)
 
diff --git a/src/Haste/Opts.hs b/src/Haste/Opts.hs
--- a/src/Haste/Opts.hs
+++ b/src/Haste/Opts.hs
@@ -191,7 +191,7 @@
     "the interpreter. This behavior can be controlled using the --onload, --onexec",
     "and --start options.",
     "",
-    "A summary of the available options are given below."
+    "A summary of the available options is given below."
   ]
 
 -- | Like 'words', except it breaks on commas instead of spaces.
diff --git a/src/Haste/PrimOps.hs b/src/Haste/PrimOps.hs
--- a/src/Haste/PrimOps.hs
+++ b/src/Haste/PrimOps.hs
@@ -233,10 +233,12 @@
     WriteOffAddrOp_Int8    -> writeOffAddr xs "i8"  1
     WriteOffAddrOp_Int16   -> writeOffAddr xs "i16" 2
     WriteOffAddrOp_Int32   -> writeOffAddr xs "i32" 4
+    WriteOffAddrOp_Int64   -> writeOffAddr64 xs
     WriteOffAddrOp_Word    -> writeOffAddr xs "w32" 4
     WriteOffAddrOp_Word8   -> writeOffAddr xs "w8"  1
     WriteOffAddrOp_Word16  -> writeOffAddr xs "w16" 2
     WriteOffAddrOp_Word32  -> writeOffAddr xs "w32" 4
+    WriteOffAddrOp_Word64  -> writeOffAddr64 xs
     WriteOffAddrOp_WideChar-> writeOffAddr xs "w32" 4
     WriteOffAddrOp_Float   -> writeOffAddr xs "f32" 4
     WriteOffAddrOp_Double  -> writeOffAddr xs "f64" 8
@@ -245,10 +247,12 @@
     ReadOffAddrOp_Int8     -> readOffAddr xs "i8"   1
     ReadOffAddrOp_Int16    -> readOffAddr xs "i16"  2
     ReadOffAddrOp_Int32    -> readOffAddr xs "i32"  4
+    ReadOffAddrOp_Int64    -> readOffAddr64 xs True
     ReadOffAddrOp_Word     -> readOffAddr xs "w32"  4
     ReadOffAddrOp_Word8    -> readOffAddr xs "w8"   1
     ReadOffAddrOp_Word16   -> readOffAddr xs "w16"  2
     ReadOffAddrOp_Word32   -> readOffAddr xs "w32"  4
+    ReadOffAddrOp_Word64   -> readOffAddr64 xs False
     ReadOffAddrOp_WideChar -> readOffAddr xs "w32"  4
     ReadOffAddrOp_Float    -> readOffAddr xs "f32"  4
     ReadOffAddrOp_Double   -> readOffAddr xs "f64"  8
@@ -357,11 +361,15 @@
       Right $ callForeign "writeOffAddr" [litS etype,litN esize,addr,off,rhs]
     writeOffAddr _ _ _ =
       error "writeOffAddr primop with too few arguments!"
+    writeOffAddr64 (addr:off:rhs:_) =
+      Right $ callForeign "writeOffAddr64" [addr, off, rhs]
     
     readOffAddr (addr:off:_) etype esize =
       Right $ callForeign "readOffAddr" [litS etype,litN esize,addr,off]
     readOffAddr _ _ _ =
       error "readOffAddr primop with too few arguments!"
+    readOffAddr64 (addr:off:_) esigned =
+      Right $ callForeign "readOffAddr64" [lit esigned, addr, off]
 
     callF f = Right $ callForeign f xs
     
diff --git a/src/Haste/Version.hs b/src/Haste/Version.hs
--- a/src/Haste/Version.hs
+++ b/src/Haste/Version.hs
@@ -5,6 +5,7 @@
     showBootVersion, parseBootVersion,
     showVersion
   ) where
+import Paths_haste_compiler
 import Data.Version
 import Config (cProjectVersion)
 import Text.ParserCombinators.ReadP
@@ -12,7 +13,7 @@
 
 -- | Current Haste version.
 hasteVersion :: Version
-hasteVersion = Version [0,5,4,2] []
+hasteVersion = version
 
 -- | Current Haste version as an Int. The format of this version number is
 --   MAJOR*10 000 + MINOR*100 + MICRO.
diff --git a/src/haste-boot.hs b/src/haste-boot.hs
--- a/src/haste-boot.hs
+++ b/src/haste-boot.hs
@@ -146,7 +146,7 @@
 hdr :: String
 hdr = "Fetch, build and install all libraries necessary to use Haste.\n"
 
-data CabalOp = Configure | Build | Install | Clean
+data CabalOp = Configure | Build | Install | Clean | Do String
 
 main :: IO ()
 main = shell_ $ do
@@ -343,8 +343,23 @@
                          , "-f-integer-gmp"
                          , "-f-sse2"
                          , "-f-sse41"
-                         , "./haste-lib"]
+                         , "./haste-lib"
+                         ]
 
+      -- Install QuickCheck
+      libdir <- pwd
+      inTempDirectory $ do
+        hasteCabal (Do "unpack") ["QuickCheck-2.6"]
+        inDirectory "QuickCheck-2.6" $ do
+          run_ "patch" [ "-p1"
+                       , "-i"
+                       , libdir </> "quickcheck-2.6-amp.patch"
+                       ] ""
+        hasteCabal Install [ "-f-templatehaskell"
+                           , "--allow-newer=base"
+                           , "./QuickCheck-2.6"
+                           ]
+
       -- Export monads-tf; it seems to be hidden by default
       run_ hastePkgBinary ["expose", "monads-tf"] ""
   where
@@ -376,6 +391,9 @@
     hasteCabal Clean args =
       withEnv "HASTE_BOOTING" (const "1") $ run_ hasteCabalBinary as ""
       where as = "clean" : args
+    hasteCabal (Do what) args =
+      withEnv "HASTE_BOOTING" (const "1") $ run_ hasteCabalBinary as ""
+      where as = what : args
 
     vanillaCabal args = run_ "cabal" args ""