diff --git a/src/commands/registration/appe.js b/src/commands/registration/appe.js
index 01fced5..afeb329 100644
--- a/src/commands/registration/appe.js
+++ b/src/commands/registration/appe.js
@@ -7,4 +7,4 @@ module.exports = {
   },
   syntax: '{{cmd}} [path]',
   description: 'Append to a file'
-}
+};
diff --git a/src/commands/registration/auth.js b/src/commands/registration/auth.js
index 4d570ca..4ad9ec6 100644
--- a/src/commands/registration/auth.js
+++ b/src/commands/registration/auth.js
@@ -16,7 +16,7 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
 
 function handleTLS() {
   return this.reply(504);
diff --git a/src/commands/registration/cdup.js b/src/commands/registration/cdup.js
index a37a6e7..ac72f8d 100644
--- a/src/commands/registration/cdup.js
+++ b/src/commands/registration/cdup.js
@@ -2,10 +2,10 @@ const cwd = require('./cwd').handler;
 
 module.exports = {
   directive: ['CDUP', 'XCUP'],
-  handler: function(args) {
+  handler: function (args) {
     args.command._ = [args.command._[0], '..'];
     return cwd.call(this, args);
   },
   syntax: '{{cmd}}',
   description: 'Change to Parent Directory'
-}
+};
diff --git a/src/commands/registration/cwd.js b/src/commands/registration/cwd.js
index d8dfa57..1977ce9 100644
--- a/src/commands/registration/cwd.js
+++ b/src/commands/registration/cwd.js
@@ -7,7 +7,7 @@ module.exports = {
     if (!this.fs) return this.reply(550, 'File system not instantiated');
     if (!this.fs.chdir) return this.reply(402, 'Not supported by file system');
 
-    return when(this.fs.chdir(command._[1]))
+    return when.try(this.fs.chdir.bind(this.fs), command._[1])
     .then(cwd => {
       const path = cwd ? `"${escapePath(cwd)}"` : undefined;
       return this.reply(250, path);
@@ -19,4 +19,4 @@ module.exports = {
   },
   syntax: '{{cmd}}[path]',
   description: 'Change working directory'
-}
+};
diff --git a/src/commands/registration/dele.js b/src/commands/registration/dele.js
index ca06ba3..e843c28 100644
--- a/src/commands/registration/dele.js
+++ b/src/commands/registration/dele.js
@@ -6,7 +6,7 @@ module.exports = {
     if (!this.fs) return this.reply(550, 'File system not instantiated');
     if (!this.fs.delete) return this.reply(402, 'Not supported by file system');
 
-    return when(this.fs.delete(command._[1]))
+    return when.try(this.fs.delete.bind(this.fs), command._[1])
     .then(() => {
       return this.reply(250);
     })
@@ -17,4 +17,4 @@ module.exports = {
   },
   syntax: '{{cmd}} [path]',
   description: 'Delete file'
-}
+};
diff --git a/src/commands/registration/feat.js b/src/commands/registration/feat.js
index 2135e5d..56ea0f0 100644
--- a/src/commands/registration/feat.js
+++ b/src/commands/registration/feat.js
@@ -18,4 +18,4 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
diff --git a/src/commands/registration/help.js b/src/commands/registration/help.js
index 450023d..a6d8ba4 100644
--- a/src/commands/registration/help.js
+++ b/src/commands/registration/help.js
@@ -21,4 +21,4 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
diff --git a/src/commands/registration/list.js b/src/commands/registration/list.js
index 4c54f4a..8952d4d 100644
--- a/src/commands/registration/list.js
+++ b/src/commands/registration/list.js
@@ -6,7 +6,7 @@ const getFileStat = require('../../helpers/file-stat');
 // http://cr.yp.to/ftp/list/eplf.html
 module.exports = {
   directive: 'LIST',
-  handler: function ({log, command, previous_command} = {}) {
+  handler: function ({log, command} = {}) {
     if (!this.fs) return this.reply(550, 'File system not instantiated');
     if (!this.fs.list) return this.reply(402, 'Not supported by file system');
 
@@ -19,9 +19,9 @@ module.exports = {
       this.commandSocket.pause();
       dataSocket = socket;
     })
-    .then(() => when(this.fs.list(directory)))
+    .then(() => when.try(this.fs.list.bind(this.fs), directory))
     .then(files => {
-      const getFileMessage = (file) => {
+      const getFileMessage = file => {
         if (simple) return file.name;
         return getFileStat(file, _.get(this, 'server.options.file_format', 'ls'));
       };
@@ -33,7 +33,7 @@ module.exports = {
           message,
           socket: dataSocket
         };
-      })
+      });
       return this.reply(150)
       .then(() => {
         if (fileList.length) return this.reply({}, ...fileList);
@@ -57,4 +57,4 @@ module.exports = {
   },
   syntax: '{{cmd}} [path(optional)]',
   description: 'Returns information of a file or directory if specified, else information of the current working directory is returned'
-}
+};
diff --git a/src/commands/registration/mdtm.js b/src/commands/registration/mdtm.js
index af01a68..9e59c70 100644
--- a/src/commands/registration/mdtm.js
+++ b/src/commands/registration/mdtm.js
@@ -7,10 +7,10 @@ module.exports = {
     if (!this.fs) return this.reply(550, 'File system not instantiated');
     if (!this.fs.get) return this.reply(402, 'Not supported by file system');
 
-    return when(this.fs.get(command._[1]))
+    return when.try(this.fs.get.bind(this.fs), command._[1])
     .then(fileStat => {
       const modificationTime = format(fileStat.mtime, 'YYYYMMDDHHmmss.SSS');
-      return this.reply(213, modificationTime)
+      return this.reply(213, modificationTime);
     })
     .catch(err => {
       log.error(err);
@@ -22,4 +22,4 @@ module.exports = {
   flags: {
     feat: 'MDTM'
   }
-}
+};
diff --git a/src/commands/registration/mkd.js b/src/commands/registration/mkd.js
index 3898905..2b48c85 100644
--- a/src/commands/registration/mkd.js
+++ b/src/commands/registration/mkd.js
@@ -7,7 +7,7 @@ module.exports = {
     if (!this.fs) return this.reply(550, 'File system not instantiated');
     if (!this.fs.mkdir) return this.reply(402, 'Not supported by file system');
 
-    return when(this.fs.mkdir(command._[1]))
+    return when.try(this.fs.mkdir.bind(this.fs), command._[1])
     .then(dir => {
       const path = dir ? `"${escapePath(dir)}"` : undefined;
       return this.reply(257, path);
@@ -19,4 +19,4 @@ module.exports = {
   },
   syntax: '{{cmd}}[path]',
   description: 'Make directory'
-}
+};
diff --git a/src/commands/registration/mode.js b/src/commands/registration/mode.js
index 994a6ad..3b89672 100644
--- a/src/commands/registration/mode.js
+++ b/src/commands/registration/mode.js
@@ -8,4 +8,4 @@ module.exports = {
   flags: {
     obsolete: true
   }
-}
+};
diff --git a/src/commands/registration/nlst.js b/src/commands/registration/nlst.js
index 7cea946..65e1f89 100644
--- a/src/commands/registration/nlst.js
+++ b/src/commands/registration/nlst.js
@@ -7,4 +7,4 @@ module.exports = {
   },
   syntax: '{{cmd}} [path(optional)]',
   description: 'Returns a list of file names in a specified directory'
-}
+};
diff --git a/src/commands/registration/noop.js b/src/commands/registration/noop.js
index b462a3d..a6cbe6f 100644
--- a/src/commands/registration/noop.js
+++ b/src/commands/registration/noop.js
@@ -8,4 +8,4 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
diff --git a/src/commands/registration/opts.js b/src/commands/registration/opts.js
index 10ac98d..1f27155 100644
--- a/src/commands/registration/opts.js
+++ b/src/commands/registration/opts.js
@@ -5,4 +5,4 @@ module.exports = {
   },
   syntax: '{{cmd}}',
   description: 'Select options for a feature'
-}
+};
diff --git a/src/commands/registration/pass.js b/src/commands/registration/pass.js
index a774a8a..d52af50 100644
--- a/src/commands/registration/pass.js
+++ b/src/commands/registration/pass.js
@@ -24,4 +24,4 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
diff --git a/src/commands/registration/pasv.js b/src/commands/registration/pasv.js
index d2eeb1c..3687eea 100644
--- a/src/commands/registration/pasv.js
+++ b/src/commands/registration/pasv.js
@@ -2,7 +2,7 @@ const PassiveConnector = require('../../connector/passive');
 
 module.exports = {
   directive: 'PASV',
-  handler: function ({command} = {}) {
+  handler: function () {
     this.connector = new PassiveConnector(this);
     return this.connector.setupServer()
     .then(server => {
@@ -17,4 +17,4 @@ module.exports = {
   },
   syntax: '{{cmd}}',
   description: 'Initiate passive mode'
-}
+};
diff --git a/src/commands/registration/port.js b/src/commands/registration/port.js
index d3d2556..f64d287 100644
--- a/src/commands/registration/port.js
+++ b/src/commands/registration/port.js
@@ -12,10 +12,10 @@ module.exports = {
     const port = portBytes[0] * 256 + portBytes[1];
 
     return this.connector.setupConnection(ip, port)
-    .then(socket => {
+    .then(() => {
       return this.reply(200);
-    })
+    });
   },
   syntax: '{{cmd}} [x,x,x,x,y,y]',
   description: 'Specifies an address and port to which the server should connect'
-}
+};
diff --git a/src/commands/registration/pwd.js b/src/commands/registration/pwd.js
index dce520e..def35db 100644
--- a/src/commands/registration/pwd.js
+++ b/src/commands/registration/pwd.js
@@ -3,11 +3,11 @@ const escapePath = require('../../helpers/escape-path');
 
 module.exports = {
   directive: ['PWD', 'XPWD'],
-  handler: function ({log, command} = {}) {
+  handler: function ({log} = {}) {
     if (!this.fs) return this.reply(550, 'File system not instantiated');
     if (!this.fs.currentDirectory) return this.reply(402, 'Not supported by file system');
 
-    return when(this.fs.currentDirectory())
+    return when.try(this.fs.currentDirectory.bind(this.fs))
     .then(cwd => {
       const path = cwd ? `"${escapePath(cwd)}"` : undefined;
       return this.reply(257, path);
@@ -15,8 +15,8 @@ module.exports = {
     .catch(err => {
       log.error(err);
       return this.reply(550, err.message);
-    })
+    });
   },
   syntax: '{{cmd}}',
   description: 'Print current working directory'
-}
+};
diff --git a/src/commands/registration/quit.js b/src/commands/registration/quit.js
index d3350fa..8214146 100644
--- a/src/commands/registration/quit.js
+++ b/src/commands/registration/quit.js
@@ -8,4 +8,4 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
diff --git a/src/commands/registration/retr.js b/src/commands/registration/retr.js
index e557b1c..1e8f4b8 100644
--- a/src/commands/registration/retr.js
+++ b/src/commands/registration/retr.js
@@ -12,7 +12,7 @@ module.exports = {
       this.commandSocket.pause();
       dataSocket = socket;
     })
-    .then(() => when(this.fs.read(command._[1])))
+    .then(() => when.try(this.fs.read.bind(this.fs), command._[1]))
     .then(stream => {
       return when.promise((resolve, reject) => {
         dataSocket.on('error', err => stream.emit('error', err));
@@ -34,8 +34,8 @@ module.exports = {
     .finally(() => {
       this.connector.end();
       this.commandSocket.resume();
-    })
+    });
   },
   syntax: '{{cmd}} [path]',
   description: 'Retrieve a copy of the file'
-}
+};
diff --git a/src/commands/registration/rmd.js b/src/commands/registration/rmd.js
index 3bdaf44..65f5f9a 100644
--- a/src/commands/registration/rmd.js
+++ b/src/commands/registration/rmd.js
@@ -7,4 +7,4 @@ module.exports = {
   },
   syntax: '{{cmd}} [path]',
   description: 'Remove a directory'
-}
+};
diff --git a/src/commands/registration/rnfr.js b/src/commands/registration/rnfr.js
index 020b93a..c84e59f 100644
--- a/src/commands/registration/rnfr.js
+++ b/src/commands/registration/rnfr.js
@@ -7,7 +7,7 @@ module.exports = {
     if (!this.fs.get) return this.reply(402, 'Not supported by file system');
 
     const fileName = command._[1];
-    return when(this.fs.get(fileName))
+    return when.try(this.fs.get.bind(this.fs), fileName)
     .then(() => {
       this.renameFrom = fileName;
       return this.reply(350);
diff --git a/src/commands/registration/rnto.js b/src/commands/registration/rnto.js
index dcfb4b3..755c714 100644
--- a/src/commands/registration/rnto.js
+++ b/src/commands/registration/rnto.js
@@ -11,7 +11,7 @@ module.exports = {
     const from = this.renameFrom;
     const to = command._[1];
 
-    return when(this.fs.rename(from, to))
+    return when.try(this.fs.rename.bind(this.fs), from, to)
     .then(() => {
       return this.reply(250);
     })
@@ -21,8 +21,8 @@ module.exports = {
     })
     .finally(() => {
       delete this.renameFrom;
-    })
+    });
   },
   syntax: '{{cmd}} [name]',
   description: 'Rename to'
-}
+};
diff --git a/src/commands/registration/site/chmod.js b/src/commands/registration/site/chmod.js
index 9210a95..92b6d64 100644
--- a/src/commands/registration/site/chmod.js
+++ b/src/commands/registration/site/chmod.js
@@ -10,5 +10,5 @@ module.exports = function ({log, command} = {}) {
   .catch(err => {
     log.error(err);
     return this.reply(500);
-  })
+  });
 };
diff --git a/src/commands/registration/site/index.js b/src/commands/registration/site/index.js
index bc3b0be..ee1a04a 100644
--- a/src/commands/registration/site/index.js
+++ b/src/commands/registration/site/index.js
@@ -14,10 +14,10 @@ module.exports = {
     const subCommand = {
       _: [subverb, ...subparameters],
       directive: subverb
-    }
+    };
     const handler = registry[subverb].handler.bind(this);
     return when.try(handler, { log: subLog, command: subCommand });
   },
   syntax: '{{cmd}} [subVerb] [subParams]',
   description: 'Sends site specific commands to remote server'
-}
+};
diff --git a/src/commands/registration/size.js b/src/commands/registration/size.js
index d9fc660..2f1a625 100644
--- a/src/commands/registration/size.js
+++ b/src/commands/registration/size.js
@@ -6,7 +6,7 @@ module.exports = {
     if (!this.fs) return this.reply(550, 'File system not instantiated');
     if (!this.fs.get) return this.reply(402, 'Not supported by file system');
 
-    return when(this.fs.get(command._[1]))
+    return when.try(this.fs.get.bind(this.fs), command._[1])
     .then(fileStat => {
       return this.reply(213, {message: fileStat.size});
     })
@@ -20,4 +20,4 @@ module.exports = {
   flags: {
     feat: 'SIZE'
   }
-}
+};
diff --git a/src/commands/registration/stat.js b/src/commands/registration/stat.js
index ab236c5..4aa1843 100644
--- a/src/commands/registration/stat.js
+++ b/src/commands/registration/stat.js
@@ -6,15 +6,17 @@ module.exports = {
   directive: 'STAT',
   handler: function (args = {}) {
     const {log, command} = args;
-    const path = command._[1];
+    const path = _.get(command, '_[1]');
     if (path) {
       if (!this.fs) return this.reply(550, 'File system not instantiated');
       if (!this.fs.get) return this.reply(402, 'Not supported by file system');
 
-      return when(this.fs.get(path))
+      return when.try(this.fs.get.bind(this.fs), path)
       .then(stat => {
         if (stat.isDirectory()) {
-          return when(this.fs.list(path))
+          if (!this.fs.list) return this.reply(402, 'Not supported by file system');
+
+          return when.try(this.fs.list.bind(this.fs), path)
           .then(files => {
             const fileList = files.map(file => {
               const message = getFileStat(file, _.get(this, 'server.options.file_format', 'ls'));
@@ -22,21 +24,21 @@ module.exports = {
                 raw: true,
                 message
               };
-            })
+            });
             return this.reply(213, 'Status begin', ...fileList, 'Status end');
-          })
+          });
         } else {
-          return this.reply(212, getFileStat(stat, _.get(this, 'server.options.file_format', 'ls')))
+          return this.reply(212, getFileStat(stat, _.get(this, 'server.options.file_format', 'ls')));
         }
       })
       .catch(err => {
         log.error(err);
         return this.reply(450);
-      })
+      });
     } else {
       return this.reply(211, 'Status OK');
     }
   },
   syntax: '{{cmd}} [path(optional)]',
   description: 'Returns the current status'
-}
+};
diff --git a/src/commands/registration/stor.js b/src/commands/registration/stor.js
index cc8d910..2575d67 100644
--- a/src/commands/registration/stor.js
+++ b/src/commands/registration/stor.js
@@ -15,7 +15,7 @@ module.exports = {
       this.commandSocket.pause();
       dataSocket = socket;
     })
-    .then(() => when(this.fs.write(fileName, {append})))
+    .then(() => when.try(this.fs.write.bind(this.fs), fileName, {append}))
     .then(stream => {
       return when.promise((resolve, reject) => {
         stream.on('error', err => dataSocket.emit('error', err));
@@ -41,4 +41,4 @@ module.exports = {
   },
   syntax: '{{cmd}} [path]',
   description: 'Store data as a file at the server site'
-}
+};
diff --git a/src/commands/registration/stou.js b/src/commands/registration/stou.js
index 9582315..6720bb6 100644
--- a/src/commands/registration/stou.js
+++ b/src/commands/registration/stou.js
@@ -1,3 +1,5 @@
+const when = require('when');
+
 const stor = require('./stor').handler;
 
 module.exports = {
@@ -7,9 +9,11 @@ module.exports = {
     if (!this.fs.get || !this.fs.getUniqueName) return this.reply(402, 'Not supported by file system');
 
     const fileName = args.command._[1];
-    return this.fs.get(fileName)
-    .catch(() => fileName)                // does not exist, name is unique
-    .then(() => this.fs.getUniqueName())  // exists, must create new unique name
+    return when.try(() => {
+      return when.try(this.fs.get.bind(this.fs), fileName)
+      .then(() => when.try(this.fs.getUniqueName.bind(this.fs)))
+      .catch(() => when.resolve(fileName));
+    })
     .then(name => {
       args.command._[1] = name;
       return stor.call(this, args);
diff --git a/src/commands/registration/stru.js b/src/commands/registration/stru.js
index 68470c1..cb4484d 100644
--- a/src/commands/registration/stru.js
+++ b/src/commands/registration/stru.js
@@ -8,4 +8,4 @@ module.exports = {
   flags: {
     obsolete: true
   }
-}
+};
diff --git a/src/commands/registration/syst.js b/src/commands/registration/syst.js
index 1b1e155..5e65d81 100644
--- a/src/commands/registration/syst.js
+++ b/src/commands/registration/syst.js
@@ -8,4 +8,4 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
diff --git a/src/commands/registration/user.js b/src/commands/registration/user.js
index b8a2608..b7cb8ff 100644
--- a/src/commands/registration/user.js
+++ b/src/commands/registration/user.js
@@ -2,7 +2,10 @@ module.exports = {
   directive: 'USER',
   handler: function ({log, command} = {}) {
     if (this.username) return this.reply(530, 'Username already set');
+
     this.username = command._[1];
+    if (!this.username) return this.reply(501, 'Must send username requirement');
+
     if (this.server.options.anonymous === true) {
       return this.login(this.username, '@anonymous')
       .then(() => {
@@ -20,4 +23,4 @@ module.exports = {
   flags: {
     no_auth: true
   }
-}
+};
diff --git a/src/commands/registry.js b/src/commands/registry.js
index 12ab572..86f19e3 100644
--- a/src/commands/registry.js
+++ b/src/commands/registry.js
@@ -1,3 +1,4 @@
+/* eslint no-return-assign: 0 */
 const commands = [
   require('./registration/abor'),
   require('./registration/allo'),