diff --git a/javascript-extras.cabal b/javascript-extras.cabal
--- a/javascript-extras.cabal
+++ b/javascript-extras.cabal
@@ -1,5 +1,5 @@
 name:                javascript-extras
-version:             0.2.0.0
+version:             0.2.0.1
 synopsis:            Extra javascript functions when using GHCJS
 description:         Extra javascript functions when using GHCJS
 homepage:            https://github.com/louispan/javascript-extras#readme
@@ -17,9 +17,10 @@
   hs-source-dirs:      src
   js-sources:          jsbits/extras.js
   exposed-modules:     JavaScript.Extras
-                       JavaScript.Extras.String
-                       JavaScript.Extras.Recast
+                       JavaScript.Extras.Number
                        JavaScript.Extras.Property
+                       JavaScript.Extras.Recast
+                       JavaScript.Extras.String
   build-depends:       base >= 4.7 && < 5
                      , deepseq >= 1.4 && < 2
                      , parallel >= 3.2 && < 4
diff --git a/src/JavaScript/Extras.hs b/src/JavaScript/Extras.hs
--- a/src/JavaScript/Extras.hs
+++ b/src/JavaScript/Extras.hs
@@ -1,9 +1,11 @@
 module JavaScript.Extras
-    ( module JavaScript.Extras.String
+    ( module JavaScript.Extras.Number
     , module JavaScript.Extras.Property
     , module JavaScript.Extras.Recast
+    , module JavaScript.Extras.String
     ) where
 
-import JavaScript.Extras.String
+import JavaScript.Extras.Number
 import JavaScript.Extras.Property
 import JavaScript.Extras.Recast
+import JavaScript.Extras.String
diff --git a/src/JavaScript/Extras/Number.hs b/src/JavaScript/Extras/Number.hs
new file mode 100644
--- /dev/null
+++ b/src/JavaScript/Extras/Number.hs
@@ -0,0 +1,21 @@
+{-# LANGUAGE CPP #-}
+
+module JavaScript.Extras.Number
+    ( maxSafeInteger
+    ) where
+
+maxSafeInteger :: Int
+maxSafeInteger = js_maxSafeInteger
+
+#ifdef __GHCJS__
+
+foreign import javascript unsafe
+  "Number.MAX_SAFE_INTEGER"
+  js_maxSafeInteger :: Int64
+
+#else
+
+js_maxSafeInteger :: Int
+js_maxSafeInteger = 0
+
+#endif