diff --git a/posts.py b/posts.py
index d64397055..d9695ada9 100644
--- a/posts.py
+++ b/posts.py
@@ -31,6 +31,7 @@ from session import postImage
 from webfinger import webfingerHandle
 from httpsig import createSignedHeader
 from siteactive import siteIsActive
+from utils import removeInvalidCharacters
 from utils import fileLastModified
 from utils import isPublicPost
 from utils import hasUsersPath
@@ -823,7 +824,7 @@ def validContentWarning(cw: str) -> str:
     # so remove them
     if '#' in cw:
         cw = cw.replace('#', '').replace('  ', ' ')
-    return cw
+    return removeInvalidCharacters(cw)
 
 
 def _loadAutoCW(baseDir: str, nickname: str, domain: str) -> []:
@@ -880,6 +881,8 @@ def _createPostBase(baseDir: str, nickname: str, domain: str, port: int,
                     eventStatus=None, ticketUrl=None) -> {}:
     """Creates a message
     """
+    content = removeInvalidCharacters(content)
+
     subject = _addAutoCW(baseDir, nickname, domain, subject, content)
 
     if nickname != 'news':
diff --git a/utils.py b/utils.py
index 6e9b82e2b..2755cb846 100644
--- a/utils.py
+++ b/utils.py
@@ -18,6 +18,13 @@ from followingCalendar import addPersonToCalendar
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import hashes
 
+# posts containing these strings will always get screened out,
+# both incoming and outgoing.
+# Could include dubious clacks or admin dogwhistles
+invalidCharacters = (
+    '卐', '卍', '࿕', '࿖', '࿗', '࿘'
+)
+
 
 def getSHA256(msg: str):
     """Returns a SHA256 hash of the given string
@@ -514,17 +521,23 @@ def isEvil(domain: str) -> bool:
 
 def containsInvalidChars(jsonStr: str) -> bool:
     """Does the given json string contain invalid characters?
-    e.g. dubious clacks/admin dogwhistles
     """
-    invalidStrings = {
-        '卐', '卍', '࿕', '࿖', '࿗', '࿘'
-    }
-    for isInvalid in invalidStrings:
+    for isInvalid in invalidCharacters:
         if isInvalid in jsonStr:
             return True
     return False
 
 
+def removeInvalidCharacters(text: str) -> str:
+    """Removes any invalid characters from a string
+    """
+    for isInvalid in invalidCharacters:
+        if isInvalid not in text:
+            continue
+        text = text.replace(isInvalid, '')
+    return text
+
+
 def createPersonDir(nickname: str, domain: str, baseDir: str,
                     dirname: str) -> str:
     """Create a directory for a person