diff --git a/src/filesystem/implementation.js b/src/filesystem/implementation.js
index 88fa6c6..55e92d3 100644
--- a/src/filesystem/implementation.js
+++ b/src/filesystem/implementation.js
@@ -548,7 +548,11 @@ function remove_directory(context, path, callback) {
   find_node(context, parentPath, read_parent_directory_data);
 }
 
-function open_file(context, path, flags, callback) {
+function open_file(context, path, flags, mode, callback) {
+  if (typeof mode === 'function'){
+    callback = mode;
+    mode = null;
+  }
   path = normalize(path);
   var name = basename(path);
   var parentPath = dirname(path);
@@ -660,6 +664,9 @@ function open_file(context, path, flags, callback) {
       }
       fileNode = result;
       fileNode.nlinks += 1;
+      if(mode){
+        Node.setMode(mode, fileNode);
+      }
       context.putObject(fileNode.id, fileNode, write_file_data);
     });
   }
@@ -1629,23 +1636,14 @@ function pathCheck(path, allowRelative, callback) {
 
 
 function open(fs, context, path, flags, mode, callback) {
-  /**
-   * NOTE: we support the same signature as node with a `mode` arg,
-   * but ignore it. We need to add it.  Here is what node.js does:
-   * function open(path, flags, mode, callback) {
-   *    path = getPathFromURL(path);
-   *  validatePath(path);
-   *  const flagsNumber = stringToFlags(flags);
-   *  if (arguments.length < 4) {
-   *    callback = makeCallback(mode);
-   *    mode = 0o666;
-   *  } else {
-   *    mode = validateAndMaskMode(mode, 'mode', 0o666);
-   *    callback = makeCallback(callback);
-   * }
-  */
-
-  callback = arguments[arguments.length - 1];
+  if (arguments.length < 6 ){
+    callback = arguments[arguments.length - 1];
+    mode = 0o644;
+  }
+  else {
+    mode = validateAndMaskMode(mode, FULL_READ_WRITE_EXEC_PERMISSIONS, callback);
+  }
+    
   if(!pathCheck(path, callback)) return;
 
   function check_result(error, fileNode) {
@@ -1669,7 +1667,7 @@ function open(fs, context, path, flags, mode, callback) {
     callback(new Errors.EINVAL('flags is not valid'), path);
   }
 
-  open_file(context, path, flags, check_result);
+  open_file(context, path, flags, mode, check_result);
 }
 
 function close(fs, context, fd, callback) {
diff --git a/tests/spec/fs.open.spec.js b/tests/spec/fs.open.spec.js
index 685a27d..5da8c6e 100644
--- a/tests/spec/fs.open.spec.js
+++ b/tests/spec/fs.open.spec.js
@@ -106,6 +106,39 @@ describe('fs.open', function() {
     });
   });
 
+
+  it('should create a new file, when flagged for write, and set the mode to the passed value', function(done) {
+
+    var fs = util.fs();
+    fs.open('/myfile', 'w', 0o777, function(error) {
+      if(error) throw error;
+
+      fs.stat('/myfile', function(error, result) {
+        expect(error).not.to.exist;
+        expect(result).to.exist;
+        expect(result.mode).to.exist;
+        expect(result.mode & 0o777).to.equal(0o777);
+        done();
+      });
+    });
+  });
+
+  it('should create a new file, but no mode is passed, so  the default value of 644 should be seen', function(done) {
+
+    var fs = util.fs();
+    fs.open('/myfile', 'w', function(error) {
+      if(error) throw error;
+
+      fs.stat('/myfile', function(error, result) {
+        expect(error).not.to.exist;
+        expect(result).to.exist;
+        expect(result.mode).to.exist;
+        expect(result.mode & 0o644).to.equal(0o644);
+        done();
+      });
+    });
+  });
+
   /**
    * This test is currently correct per our code, but incorrect according to the spec.
    * When we fix https://github.com/filerjs/filer/issues/314 we'll have to update this.