diff --git a/bookwyrm/templates/snippets/reply_form.html b/bookwyrm/templates/snippets/reply_form.html
index 787a3ac54..8150b8a5e 100644
--- a/bookwyrm/templates/snippets/reply_form.html
+++ b/bookwyrm/templates/snippets/reply_form.html
@@ -9,7 +9,7 @@
 
             {% include 'snippets/content_warning_field.html' with parent_status=activity %}
             <div class="field">
-                <textarea class="textarea" name="content" placeholder="Leave a comment..." id="id_content_{{ activity.id }}-{{ uuid }}" required="true"></textarea>
+                <textarea class="textarea" name="content" placeholder="Leave a comment..." id="id_content_{{ activity.id }}-{{ uuid }}" required="true">{{ activity|mentions:request.user }}</textarea>
             </div>
         </div>
         <div class="column is-narrow">
diff --git a/bookwyrm/templatetags/bookwyrm_tags.py b/bookwyrm/templatetags/bookwyrm_tags.py
index 61b097bd2..89c1690a4 100644
--- a/bookwyrm/templatetags/bookwyrm_tags.py
+++ b/bookwyrm/templatetags/bookwyrm_tags.py
@@ -110,7 +110,7 @@ def get_uuid(identifier):
     return '%s%s' % (identifier, uuid4())
 
 
-@register.filter(name="post_date")
+@register.filter(name='post_date')
 def time_since(date):
     ''' concise time ago function '''
     if not isinstance(date, datetime):
@@ -133,13 +133,20 @@ def time_since(date):
     return '%ds' % delta.seconds
 
 
-@register.filter(name="to_markdown")
+@register.filter(name='to_markdown')
 def get_markdown(content):
     ''' convert markdown to html '''
     if content:
         return to_markdown(content)
     return None
 
+@register.filter(name='mentions')
+def get_mentions(status, user):
+    ''' anyone tagged or replied to in this status '''
+    mentions = set([status.user] + list(status.mention_users.all()))
+    return ' '.join(
+        '@' + get_user_identifier(m) for m in mentions if not m == user)
+
 @register.simple_tag(takes_context=True)
 def active_shelf(context, book):
     ''' check what shelf a user has a book on, if any '''