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:             0.3.1.0
+version:             0.3.2.0
 synopsis:            Extra javascript functions when using GHCJS
 description:         Extra javascript functions when using GHCJS
 homepage:            https://github.com/louispan/javascript-extras#readme
@@ -39,7 +39,7 @@
   ghc-options:         -Wall -threaded -rtsopts -with-rtsopts=-N
   cpp-options:         -DGHCJS_BROWSER
   build-depends:       base >= 4.7 && < 5
-                     , javascript-extras >= 0.3.1
+                     , javascript-extras
   default-language:    Haskell2010
   default-extensions:  ApplicativeDo
   if impl(ghcjs)
diff --git a/src/JavaScript/Extras/Property.hs b/src/JavaScript/Extras/Property.hs
--- a/src/JavaScript/Extras/Property.hs
+++ b/src/JavaScript/Extras/Property.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE GHCForeignImportPrim #-}
 
 module JavaScript.Extras.Property
@@ -11,6 +12,7 @@
 
 import Control.DeepSeq
 import Control.Parallel
+import Data.Coerce
 import qualified GHC.Exts as Exts
 import qualified GHCJS.Marshal.Pure as J
 import qualified GHCJS.Types as J
@@ -22,16 +24,18 @@
 type Property = (J.JSString, JE.JSVar)
 
 -- | get a property of any JSVal. If a null or undefined is queried, the result will also be null
-getProperty :: J.JSString -> J.JSVal -> IO JE.JSVar
-getProperty k x = let k' = J.pToJSVal k
+getProperty :: Coercible a J.JSVal => J.JSString -> a -> IO JE.JSVar
+getProperty k a = let k' = J.pToJSVal k
+                      x = coerce a
                   in if J.isUndefined x || J.isNull x
                          || J.isUndefined k' || J.isNull k'
                      then pure $ JE.JSVar J.nullRef
                      else js_unsafeGetProperty k x
 
 -- | set a property of any JSVal
-setProperty :: Property -> J.JSVal -> IO ()
-setProperty (k, v) x = let k' = J.pToJSVal k
+setProperty :: Coercible a J.JSVal => Property -> a -> IO ()
+setProperty (k, v) a = let k' = J.pToJSVal k
+                           x = coerce a
                     in if J.isUndefined x || J.isNull x
                           || J.isUndefined k' || J.isNull k'
                        then pure ()