diff --git a/fediplay/cli.py b/fediplay/cli.py
index 6f889c3..3a0d238 100644
--- a/fediplay/cli.py
+++ b/fediplay/cli.py
@@ -1,5 +1,7 @@
 '''Entry point for command-line interface.'''
 
+options = {'debug': False}
+
 import os
 path = os.path
 import sys
@@ -49,9 +51,12 @@ def get_client_credentials(instance):
     )
 
 @click.group()
-def cli():
+@click.option('-d', '--debug', is_flag=True, help='Print debug messages.')
+def cli(debug):
     '''A program to play music your friends post on Mastodon.'''
 
+    options['debug'] = debug
+
     ensure_dirs()
 
 @cli.command()
diff --git a/fediplay/mastodon.py b/fediplay/mastodon.py
index 09eb5d6..28e2db9 100644
--- a/fediplay/mastodon.py
+++ b/fediplay/mastodon.py
@@ -7,6 +7,7 @@ from lxml.etree import HTML # pylint: disable=no-name-in-module
 import mastodon
 from youtube_dl.utils import DownloadError
 
+from fediplay.cli import options
 import fediplay.keyring as keyring
 from fediplay.queue import Queue
 
@@ -25,9 +26,18 @@ class StreamListener(mastodon.StreamListener):
         self.queue = queue
         self.users = users
 
+        if options['debug']:
+            print('listener initialized with users={}'.format(self.users))
+
     def on_update(self, status):
+        if options['debug']:
+            print('incoming toot: username={}'.format(status.account.username))
+
         if self.users and status.account.username not in self.users:
+            if options['debug']:
+                print('skipping toot due to username filtering')
             return
+
         tags = extract_tags(status)
         if 'fediplay' in tags:
             links = extract_links(status)
@@ -68,7 +78,7 @@ def stream(instance, users, client_id, client_secret, access_token, cache_dir='.
     '''Stream statuses and add them to a queue.'''
 
     client = build_client(instance, client_id, client_secret, access_token)
-    users = [normalize_username(u, instance) for u in users]
+    users = [normalize_username(user, instance) for user in users]
     listener = StreamListener(Queue(cache_dir), users)
     click.echo('==> Streaming from {}'.format(instance))
     client.stream_user(listener)
@@ -85,7 +95,6 @@ def normalize_username(user, instance):
     # remove instance if it is our own instance
     return user if (len(tmp) == 1 or tmp[1] != instance) else tmp[0]
 
-
 def link_is_internal(link):
     '''Determines if a link is internal to the Mastodon instance.'''
 
diff --git a/fediplay/queue.py b/fediplay/queue.py
index ffc5d06..6b06805 100644
--- a/fediplay/queue.py
+++ b/fediplay/queue.py
@@ -8,6 +8,7 @@ from threading import Thread, Lock
 import click
 from youtube_dl import YoutubeDL, utils
 
+from fediplay.cli import options
 import fediplay.env as env
 
 
@@ -62,7 +63,13 @@ class Getter(object):
         self.cache_dir = cache_dir
 
     def _progress_hook(self, progress):
-        if progress['status'] == 'downloading' and progress['filename'] not in self.filenames:
+        if options['debug']:
+            print('progress hook: status {}, filename {}'.format(
+                progress['status'], progress['filename']
+            ))
+
+        if (progress['status'] == 'downloading' and 
+            progress['filename'] not in self.filenames):
             self.filenames.append(progress['filename'])
 
     def get(self, url):