diff --git a/src/filesystem/interface.js b/src/filesystem/interface.js
index 4cd7b9a..e9e54e1 100644
--- a/src/filesystem/interface.js
+++ b/src/filesystem/interface.js
@@ -87,6 +87,9 @@ function FileSystem(options, callback) {
   fs.stdout = STDOUT;
   fs.stderr = STDERR;
 
+  // Expose Shell constructor
+  this.Shell = Shell.bind(undefined, this);
+
   // Safely expose the list of open files and file
   // descriptor management functions
   var openFiles = {};
@@ -334,8 +337,4 @@ FileSystem.providers = providers;
   };
 });
 
-FileSystem.prototype.shell = function(options) {
-  return new Shell(this, options);
-};
-
 module.exports = FileSystem;
diff --git a/tests/bugs/issue247.js b/tests/bugs/issue247.js
index 37a4067..e69a45e 100644
--- a/tests/bugs/issue247.js
+++ b/tests/bugs/issue247.js
@@ -8,7 +8,7 @@ describe('sh.cd doesn\'t seem to be working from a relative path if I am one or
 
   it('should properly deal with relative paths missing ./ and ../', function(done) {
     var fs = util.fs();
-    var sh = fs.shell();
+    var sh = new fs.Shell();
 
     sh.mkdirp('/home/scott', function(err) {
       if(err) throw err;
diff --git a/tests/bugs/ls-depth-bug.js b/tests/bugs/ls-depth-bug.js
index 07d08f7..ac2c5ae 100644
--- a/tests/bugs/ls-depth-bug.js
+++ b/tests/bugs/ls-depth-bug.js
@@ -9,7 +9,7 @@ describe('sh.ls and deep directory trees', function() {
 
   it('should not crash when calling sh.ls() on deep directory layouts', function(done) {
     var fs = util.fs();
-    var sh = fs.shell();
+    var sh = new fs.Shell();
 
     var path = '';
     for(var i=0; i<50; i++) {
@@ -29,7 +29,7 @@ describe('sh.ls and deep directory trees', function() {
 
   it('should not crash when calling sh.ls() on wide directory layouts', function(done) {
     var fs = util.fs();
-    var sh = fs.shell();
+    var sh = new fs.Shell();
 
     var dirName = '/dir';
 
diff --git a/tests/lib/test-utils.js b/tests/lib/test-utils.js
index 55be94d..ce54388 100644
--- a/tests/lib/test-utils.js
+++ b/tests/lib/test-utils.js
@@ -85,7 +85,7 @@
   }
 
   function shell(options) {
-    return fs().shell(options);
+    return new (fs()).Shell(options);
   }
 
   function cleanup(callback) {
diff --git a/tests/spec/fs.shell.spec.js b/tests/spec/fs.shell.spec.js
index 556f350..164e5ee 100644
--- a/tests/spec/fs.shell.spec.js
+++ b/tests/spec/fs.shell.spec.js
@@ -8,14 +8,14 @@ describe("fs.shell", function() {
 
   it("is a function", function(done) {
     var fs = util.fs();
-    expect(typeof fs.shell).to.equal('function');
+    expect(typeof fs.Shell).to.equal('function');
 
     done();
   });
 
   it('should return a FileSystemShell instance', function(done) {
     var fs = util.fs();
-    var sh = fs.shell();
+    var sh = new fs.Shell();
 
     expect(sh.prototype).to.deep.equal((new Filer.Shell(fs)).prototype);
     done();
@@ -23,7 +23,7 @@ describe("fs.shell", function() {
 
   it('should reflect changes to the prototype', function(done){
     var fs = util.fs();
-    var sh = fs.shell();
+    var sh = new fs.Shell();
 
     Filer.Shell.prototype.test = "foo";
 
diff --git a/tests/spec/shell/cat.spec.js b/tests/spec/shell/cat.spec.js
index 8e3512a..e7b6d67 100644
--- a/tests/spec/shell/cat.spec.js
+++ b/tests/spec/shell/cat.spec.js
@@ -13,7 +13,7 @@ describe('FileSystemShell.cat', function() {
 
   it('should fail when files argument is absent', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     shell.cat(null, function(error, data) {
       expect(error).to.exist;
@@ -25,7 +25,7 @@ describe('FileSystemShell.cat', function() {
 
   it('should return the contents of a single file', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "file contents";
 
     fs.writeFile('/file', contents, function(err) {
@@ -41,7 +41,7 @@ describe('FileSystemShell.cat', function() {
 
   it('should return the contents of multiple files', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "file contents";
     var contents2 = contents + '\n' + contents;
 
@@ -62,7 +62,7 @@ describe('FileSystemShell.cat', function() {
 
   it('should fail if any of multiple file paths is invalid', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "file contents";
     var contents2 = contents + '\n' + contents;
 
diff --git a/tests/spec/shell/cd.spec.js b/tests/spec/shell/cd.spec.js
index 52b1dca..c45fbf8 100644
--- a/tests/spec/shell/cd.spec.js
+++ b/tests/spec/shell/cd.spec.js
@@ -18,7 +18,7 @@ describe('FileSystemShell.cd', function() {
 
   it('should allow changing the path to a valid dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -34,7 +34,7 @@ describe('FileSystemShell.cd', function() {
 
   it('should fail when changing the path to an invalid dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -51,7 +51,7 @@ describe('FileSystemShell.cd', function() {
 
   it('should fail when changing the path to a file', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.writeFile('/file', 'file', function(err) {
       if(err) throw err;
@@ -68,7 +68,7 @@ describe('FileSystemShell.cd', function() {
 
   it('should allow relative paths for a valid dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -84,7 +84,7 @@ describe('FileSystemShell.cd', function() {
 
   it('should allow .. in paths for a valid dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -111,7 +111,7 @@ describe('FileSystemShell.cd', function() {
       fs.symlink('/dir', '/link', function(error) {
         if(error) throw error;
 
-        var shell = fs.shell();
+        var shell = new fs.Shell();
         shell.cd('link', function(error) {
           expect(error).not.to.exist;
           expect(shell.pwd()).to.equal('/link');
diff --git a/tests/spec/shell/env.spec.js b/tests/spec/shell/env.spec.js
index fc072ee..5cf1c9e 100644
--- a/tests/spec/shell/env.spec.js
+++ b/tests/spec/shell/env.spec.js
@@ -34,7 +34,7 @@ describe('FileSystemShell.env', function() {
 
   it('should fail when dirs argument is absent', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     shell.cat(null, function(error, list) {
       expect(error).to.exist;
@@ -46,7 +46,7 @@ describe('FileSystemShell.env', function() {
 
   it('should give new value for shell.pwd() when cwd changes', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -62,7 +62,7 @@ describe('FileSystemShell.env', function() {
 
   it('should create/return the default tmp dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     expect(shell.env.get('TMP')).to.equal('/tmp');
     shell.tempDir(function(err, tmp) {
@@ -77,7 +77,7 @@ describe('FileSystemShell.env', function() {
 
   it('should create/return the tmp dir specified in env.TMP', function(done) {
     var fs = util.fs();
-    var shell = fs.shell({
+    var shell = new fs.Shell({
       env: {
         TMP: '/tempdir'
       }
@@ -96,7 +96,7 @@ describe('FileSystemShell.env', function() {
 
   it('should allow repeated calls to tempDir()', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     expect(shell.env.get('TMP')).to.equal('/tmp');
     shell.tempDir(function(err, tmp) {
diff --git a/tests/spec/shell/exec.spec.js b/tests/spec/shell/exec.spec.js
index ea5bbc6..ee94a42 100644
--- a/tests/spec/shell/exec.spec.js
+++ b/tests/spec/shell/exec.spec.js
@@ -13,7 +13,7 @@ describe('FileSystemShell.exec', function() {
 
   it('should be able to execute a command .js file from the filesystem', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var cmdString = "fs.writeFile(args[0], args[1], callback);";
 
     fs.writeFile('/cmd.js', cmdString, function(error) {
diff --git a/tests/spec/shell/ls.spec.js b/tests/spec/shell/ls.spec.js
index b0ad47b..c9a718d 100644
--- a/tests/spec/shell/ls.spec.js
+++ b/tests/spec/shell/ls.spec.js
@@ -13,7 +13,7 @@ describe('FileSystemShell.ls', function() {
 
   it('should fail when dirs argument is absent', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     shell.cat(null, function(error, list) {
       expect(error).to.exist;
@@ -25,7 +25,7 @@ describe('FileSystemShell.ls', function() {
 
   it('should return the contents of a simple dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "a";
     var contents2 = "bb";
 
@@ -63,7 +63,7 @@ describe('FileSystemShell.ls', function() {
 
   it('should return the shallow contents of a dir tree', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "a";
 
     fs.mkdir('/dir', function(err) {
@@ -119,7 +119,7 @@ describe('FileSystemShell.ls', function() {
 
   it('should return the deep contents of a dir tree', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "a";
 
     fs.mkdir('/dir', function(err) {
diff --git a/tests/spec/shell/mkdirp.spec.js b/tests/spec/shell/mkdirp.spec.js
index b2e7856..bbe6a04 100644
--- a/tests/spec/shell/mkdirp.spec.js
+++ b/tests/spec/shell/mkdirp.spec.js
@@ -13,7 +13,7 @@ describe('FileSystemShell.mkdirp', function() {
 
   it('should fail without a path provided', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     shell.mkdirp(null, function(err) {
       expect(err).to.exist;
@@ -24,7 +24,7 @@ describe('FileSystemShell.mkdirp', function() {
 
   it('should succeed if provided path is root', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     shell.mkdirp('/', function(err) {
       expect(err).to.not.exist;
       done();
@@ -33,7 +33,7 @@ describe('FileSystemShell.mkdirp', function() {
 
   it('should succeed if the directory exists', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     fs.mkdir('/test', function(err){
       expect(err).to.not.exist;
       shell.mkdirp('/test',function(err) {
@@ -45,7 +45,7 @@ describe('FileSystemShell.mkdirp', function() {
 
   it('fail if a file name is provided', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     fs.writeFile('/test.txt', 'test', function(err){
       expect(err).to.not.exist;
       shell.mkdirp('/test.txt', function(err) {
@@ -58,7 +58,7 @@ describe('FileSystemShell.mkdirp', function() {
 
   it('should succeed on a folder on root (\'/test\')', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     shell.mkdirp('/test', function(err) {
       expect(err).to.not.exist;
       fs.exists('/test', function(dir){
@@ -70,7 +70,7 @@ describe('FileSystemShell.mkdirp', function() {
 
   it('should succeed on a folder with a nonexistant parent (\'/test/test\')', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     shell.mkdirp('/test/test', function(err) {
       expect(err).to.not.exist;
       fs.exists('/test', function(dir1){
@@ -85,7 +85,7 @@ describe('FileSystemShell.mkdirp', function() {
 
   it('should fail on a folder with a file for its parent (\'/test.txt/test\')', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     fs.writeFile('/test.txt', 'test', function(err){
       expect(err).to.not.exist;
       shell.mkdirp('/test.txt/test', function(err) {
diff --git a/tests/spec/shell/rm.spec.js b/tests/spec/shell/rm.spec.js
index 06a3c93..0777460 100644
--- a/tests/spec/shell/rm.spec.js
+++ b/tests/spec/shell/rm.spec.js
@@ -13,7 +13,7 @@ describe('FileSystemShell.rm', function() {
 
   it('should fail when path argument is absent', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     shell.rm(null, function(error, list) {
       expect(error).to.exist;
@@ -25,7 +25,7 @@ describe('FileSystemShell.rm', function() {
 
   it('should remove a single file', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "a";
 
     fs.writeFile('/file', contents, function(err) {
@@ -45,7 +45,7 @@ describe('FileSystemShell.rm', function() {
 
   it('should remove an empty dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -64,7 +64,7 @@ describe('FileSystemShell.rm', function() {
 
   it('should fail to remove a non-empty dir', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -83,7 +83,7 @@ describe('FileSystemShell.rm', function() {
 
   it('should remove a non-empty dir with option.recursive set', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     fs.mkdir('/dir', function(err) {
       if(err) throw err;
@@ -106,7 +106,7 @@ describe('FileSystemShell.rm', function() {
 
   it('should work on a complex dir structure', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var contents = "a";
 
     fs.mkdir('/dir', function(err) {
diff --git a/tests/spec/shell/touch.spec.js b/tests/spec/shell/touch.spec.js
index bdc17b2..e37bd6a 100644
--- a/tests/spec/shell/touch.spec.js
+++ b/tests/spec/shell/touch.spec.js
@@ -20,7 +20,7 @@ describe('FileSystemShell.touch', function() {
 
   it('should create a new file if path does not exist', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     shell.touch('/newfile', function(error) {
       if(error) throw error;
@@ -35,7 +35,7 @@ describe('FileSystemShell.touch', function() {
 
   it('should skip creating a new file if options.updateOnly is true', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
 
     shell.touch('/newfile', { updateOnly: true }, function(error) {
       if(error) throw error;
@@ -49,7 +49,7 @@ describe('FileSystemShell.touch', function() {
 
   it('should update times if path does exist', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var atime = Date.parse('1 Oct 2000 15:33:22');
     var mtime = Date.parse('30 Sep 2000 06:43:54');
 
@@ -80,7 +80,7 @@ describe('FileSystemShell.touch', function() {
 
   it('should update times to specified date if path does exist', function(done) {
     var fs = util.fs();
-    var shell = fs.shell();
+    var shell = new fs.Shell();
     var date = Date.parse('1 Oct 2001 15:33:22');
 
     fs.open('/newfile', 'w', function (error, fd) {