diff --git a/src/fs.coffee b/src/fs.coffee
index 712cedbbf..34f881808 100644
--- a/src/fs.coffee
+++ b/src/fs.coffee
@@ -43,6 +43,7 @@ module.exports =
   # Returns true if the file specified by path exists and is a
   # regular file.
   isFile: (path) ->
+    path = @absolute path
     isDir = new jscocoa.outArgument
     exists = OSX.NSFileManager.defaultManager.
       fileExistsAtPath_isDirectory path, isDir