diff --git a/examples/test.html b/examples/test.html
index 5c70caf..b1adf96 100644
--- a/examples/test.html
+++ b/examples/test.html
@@ -17,6 +17,7 @@ require(["../../javascript-debug/debug", "src/filesystem"], function(debug, File
   debug.log("filesystem state: ", fs.state);
   fs.then(function(fs) {
     debug.log("filesystem state: ", fs.state);
+    fs.mkdir("/tmp");
   });
 });
 </script>
diff --git a/src/filesystem.js b/src/filesystem.js
index 894b776..ebb5b93 100644
--- a/src/filesystem.js
+++ b/src/filesystem.js
@@ -47,65 +47,26 @@ define(function(require) {
   FileError.TYPE_MISMATCH_ERR = 11;
   FileError.PATH_EXISTS_ERR = 12;
 
-  function Entry() {}
-  Entry.prototype.move = function move(parent, newName, successCallback, errorCallback) {
-  };
-  Entry.prototype.copy = function copy(parent, newName, successCallback, errorCallback) {
-  };
-  Entry.prototype.remove = function remove(successCallback, errorCallback) {
-  };
-  Entry.prototype.getParent = function getParent(successCallback, errorCallback) {
-  };
-  Entry.prototype.getMetadata = function getMetadata(successCallback, errorCallback) {
-  };
-  /*Entry.prototype.toUrl = function toUrl(mimeType) {
-  };*/
-
-  function DirectoryEntry(fs, path, name, parent) {
-    this.isFile = false;
-    this.isDirectory = true;
-    this.name = name;
-    this.path = path; // FIXME: account for the parent path
-    this.filesystem = fs;
-    this.parent = parent;
-  }
-  DirectoryEntry.prototype = new Entry();
-  DirectoryEntry.prototype.createReader = function createReader() {
-  };
-  DirectoryEntry.prototype.removeRecursively = function removeRecursively(successCallback, errorCallback) {
-  };
-  DirectoryEntry.prototype.getFile = function getFile(path, options, successCallback, errorCallback) {
-  };
-  DirectoryEntry.prototype.getDirectory = function getDirectory(path, options, successCallback, errorCallback) {
-  };
-
-  function FileEntry(fs, path, name, parent) {
-    this.isFile = true;
-    this.isDirectory = false;
-    this.name = name;
-    this.path = path; // FIXME: account for the parent path
-    this.filesystem = fs;
-    this.parent = parent;
-  }
-  FileEntry.prototype = new Entry();
-  FileEntry.prototype.createWriter = function createWriter(successCallback, errorCallback) {    
-  };
-  FileEntry.prototype.file = function file(successCallback, errorCallback) {
+  function DirectoryError(code) {
+    this.code = code;
+    // FIXME: add a message field with the text error
   };
+  DirectoryError.PATH_EXISTS_ERR = 1;
+  DirectoryError.MISSING_PATH_COMPONENT_ERR = 2;
 
   var RO = "readonly",
       RW = "readwrite";
 
   function FileSystem(name, optFormat) {
     var fs = this;
-    var FILES = "files";
+    fs.OBJECT_STORE_NAME = "files";
     fs.name = name || "default";    
     fs.pending = {};
 
     fs.state = FileSystem.UNINITIALIZED;
     var deferred;
     fs.then;
-    fs.root;
+    fs.db;
 
     function updateState() {
       if(FileSystem.READY === fs.state && Object.keys(fs.pending).length > 0) {
@@ -145,7 +106,6 @@ define(function(require) {
       return request;
     } 
 
-    var db;
     var format = undefined !== optFormat ? optFormat : false;
     var deferred = when.defer();
     fs.then = deferred.promise.then;
@@ -155,11 +115,12 @@ define(function(require) {
     fs.state = FileSystem.PENDING;
 
     openRequest.onsuccess = function(e) {
-      db = e.target.result;
+      fs.db = e.target.result;
+      var db = fs.db;
+      var transaction = db.transaction([fs.OBJECT_STORE_NAME], RW);
+      var store = transaction.objectStore(fs.OBJECT_STORE_NAME);
       if(format) {
-        debug.info("format required");
-        var transaction = db.transaction([FILES], RW);
-        var store = transaction.objectStore(FILES);
+        debug.info("format required");        
         var formatRequest = queuePending(store.put({}, "/"));
         formatRequest.onsuccess = function(e) {
           debug.info("format complete");
@@ -175,8 +136,8 @@ define(function(require) {
           db.deleteObjectStore("files");
       }
       var store = db.createObjectStore("files");
-      store.createIndex("parent", "parent");
-      store.createIndex("name", "name");
+      store.createIndex("parent", "parent", {unique: false});
+      store.createIndex("name", "name", {unique: true});
 
       format = true;
     };
@@ -184,6 +145,35 @@ define(function(require) {
     openRequest.onerror = function(e) {
       clearPending(openRequest);
     };
+
+    // API
+
+    this.mkdir = function mkdir(path) {
+      debug.info("mkdir");
+      var db = fs.db;
+      var d = when.defer();
+      var transaction = db.transaction([this.OBJECT_STORE_NAME], RW);
+      var store = transaction.objectStore(fs.OBJECT_STORE_NAME);      
+      var nameIndex = store.index("name");
+
+      var getRequest = queuePending(nameIndex.get(path));
+      getRequest.onsuccess = function(e) {
+        clearPending(getRequest);
+        var result = e.target.result;
+        if(result) {
+          debug.info("mkdir PATH_EXISTS_ERR");
+          d.reject(new DirectoryError(DirectoryError.PATH_EXISTS_ERR));
+        } else {
+          var directoryRequest = queuePending(store.put({}, path));
+          directoryRequest.onsuccess = function(e) {
+            debug.info("mkdir complete");
+            clearPending(directoryRequest);
+            d.resolve();
+          };
+        }
+      };
+      return d.promise;
+    }
   }
   FileSystem.READY = 0;
   FileSystem.PENDING = 1;