diff --git a/inbox.py b/inbox.py
index 185180ae6..bba79f8cd 100644
--- a/inbox.py
+++ b/inbox.py
@@ -126,6 +126,7 @@ from utils import dangerous_markup
 from utils import is_dm
 from utils import is_reply
 from utils import has_actor
+from utils import valid_content_warning
 from httpsig import message_content_digest
 from posts import outbox_message_create_wrap
 from posts import convert_post_content_to_html
@@ -133,7 +134,6 @@ from posts import edited_post_filename
 from posts import save_post_to_box
 from posts import is_create_inside_announce
 from posts import create_direct_message_post
-from posts import valid_content_warning
 from posts import download_announce
 from posts import is_muted_conv
 from posts import is_image_media
diff --git a/posts.py b/posts.py
index 0495b8747..bf64e510e 100644
--- a/posts.py
+++ b/posts.py
@@ -34,6 +34,7 @@ from webfinger import webfinger_handle
 from httpsig import create_signed_header
 from siteactive import site_is_active
 from languages import understood_post_language
+from utils import valid_content_warning
 from utils import get_actor_from_post_id
 from utils import string_contains
 from utils import get_post_attachments
@@ -1137,17 +1138,6 @@ def _add_schedule_post(base_dir: str, nickname: str, domain: str,
                   schedule_index_filename + ' ' + str(ex))
 
 
-def valid_content_warning(summary: str) -> str:
-    """Returns a validated content warning
-    """
-    cw_str = remove_html(summary)
-    # hashtags within content warnings apparently cause a lot of trouble
-    # so remove them
-    if '#' in cw_str:
-        cw_str = cw_str.replace('#', '').replace('  ', ' ')
-    return remove_invalid_chars(cw_str)
-
-
 def _create_post_cw_from_reply(base_dir: str, nickname: str, domain: str,
                                in_reply_to: str,
                                sensitive: bool, summary: str,
diff --git a/tests.py b/tests.py
index 04bc49f7f..857e48aff 100644
--- a/tests.py
+++ b/tests.py
@@ -42,7 +42,6 @@ from posts import get_actor_from_in_reply_to
 from posts import regenerate_index_for_box
 from posts import remove_post_interactions
 from posts import get_mentioned_people
-from posts import valid_content_warning
 from posts import delete_all_posts
 from posts import create_public_post
 from posts import send_post
@@ -56,6 +55,7 @@ from follow import clear_followers
 from follow import send_follow_request_via_server
 from follow import send_unfollow_request_via_server
 from siteactive import site_is_active
+from utils import valid_content_warning
 from utils import data_dir
 from utils import data_dir_testing
 from utils import remove_link_tracking
diff --git a/utils.py b/utils.py
index 7ed7c8244..a47c66647 100644
--- a/utils.py
+++ b/utils.py
@@ -5040,6 +5040,17 @@ def unescaped_text(txt: str) -> str:
     return txt
 
 
+def valid_content_warning(summary: str) -> str:
+    """Returns a validated content warning
+    """
+    cw_str = remove_html(summary)
+    # hashtags within content warnings apparently cause a lot of trouble
+    # so remove them
+    if '#' in cw_str:
+        cw_str = cw_str.replace('#', '').replace('  ', ' ')
+    return remove_invalid_chars(cw_str)
+
+
 def harmless_markup(post_json_object: {}) -> None:
     """render harmless any dangerous markup
     """
@@ -5048,6 +5059,12 @@ def harmless_markup(post_json_object: {}) -> None:
 
     for field_name in ('content', 'summary'):
         if post_json_object['object'].get(field_name):
+            # tidy up content warnings
+            if field_name == 'summary':
+                summary = post_json_object['object'][field_name]
+                post_json_object['object'][field_name] = \
+                    valid_content_warning(summary)
+
             if dangerous_markup(post_json_object['object'][field_name],
                                 False, ['pre']):
                 post_json_object['object'][field_name] = \