diff --git a/inbox.py b/inbox.py
index 8b8a5c76..2e467376 100644
--- a/inbox.py
+++ b/inbox.py
@@ -272,6 +272,8 @@ def inboxPermittedMessage(domain: str, messageJson: {},
             return False
         if messageJson['object'].get('inReplyTo'):
             inReplyTo = messageJson['object']['inReplyTo']
+            if not isinstance(inReplyTo, str):
+                return False
             if not urlPermitted(inReplyTo, federationList, "inbox:write"):
                 return False
 
@@ -1596,6 +1598,8 @@ def populateReplies(baseDir: str, httpPrefix: str, domain: str,
     if not messageJson['object'].get('to'):
         return False
     replyTo = messageJson['object']['inReplyTo']
+    if not isinstance(replyTo, str):
+        return False
     if debug:
         print('DEBUG: post contains a reply')
     # is this a reply to a post on this domain?
@@ -1760,6 +1764,9 @@ def obtainAvatarForReplyPost(session, baseDir: str, httpPrefix: str,
     if not lookupActor:
         return
 
+    if not isinstance(lookupActor, str):
+        return
+
     if not ('/users/' in lookupActor or
             '/accounts/' in lookupActor or
             '/channel/' in lookupActor or
diff --git a/posts.py b/posts.py
index 1517fea4..448cde45 100644
--- a/posts.py
+++ b/posts.py
@@ -388,15 +388,16 @@ def getPosts(session, outboxUrl: str, maxPosts: int,
             inReplyTo = ''
             if item['object'].get('inReplyTo'):
                 if item['object']['inReplyTo']:
-                    # No replies to non-permitted domains
-                    if not urlPermitted(item['object']['inReplyTo'],
-                                        federationList,
-                                        "objects:read"):
-                        if debug:
-                            print('url not permitted ' +
-                                  item['object']['inReplyTo'])
-                        continue
-                    inReplyTo = item['object']['inReplyTo']
+                    if isinstance(item['object']['inReplyTo'], str):
+                        # No replies to non-permitted domains
+                        if not urlPermitted(item['object']['inReplyTo'],
+                                            federationList,
+                                            "objects:read"):
+                            if debug:
+                                print('url not permitted ' +
+                                      item['object']['inReplyTo'])
+                            continue
+                        inReplyTo = item['object']['inReplyTo']
 
             conversation = ''
             if item['object'].get('conversation'):
@@ -483,10 +484,11 @@ def getPostDomains(session, outboxUrl: str, maxPosts: int,
         if not isinstance(item['object'], dict):
             continue
         if item['object'].get('inReplyTo'):
-            postDomain, postPort = \
-                getDomainFromActor(item['object']['inReplyTo'])
-            if postDomain not in postDomains:
-                postDomains.append(postDomain)
+            if isinstance(item['object']['inReplyTo'], str):
+                postDomain, postPort = \
+                    getDomainFromActor(item['object']['inReplyTo'])
+                if postDomain not in postDomains:
+                    postDomains.append(postDomain)
 
         if item['object'].get('tag'):
             for tagItem in item['object']['tag']:
@@ -2675,8 +2677,9 @@ def isReply(postJsonObject: {}, actor: str) -> bool:
        postJsonObject['object']['type'] != 'Article':
         return False
     if postJsonObject['object'].get('inReplyTo'):
-        if postJsonObject['object']['inReplyTo'].startswith(actor):
-            return True
+        if isinstance(postJsonObject['object']['inReplyTo'], str):
+            if postJsonObject['object']['inReplyTo'].startswith(actor):
+                return True
     if not postJsonObject['object'].get('tag'):
         return False
     if not isinstance(postJsonObject['object']['tag'], list):
diff --git a/question.py b/question.py
index a52a9bb0..bf328293 100644
--- a/question.py
+++ b/question.py
@@ -25,6 +25,8 @@ def questionUpdateVotes(baseDir: str, nickname: str, domain: str,
         return None
     if not replyJson['object']['inReplyTo']:
         return None
+    if not isinstance(replyJson['object']['inReplyTo'], str):
+        return None
     if not replyJson['object'].get('name'):
         return None
     inReplyTo = replyJson['object']['inReplyTo']
diff --git a/utils.py b/utils.py
index 073e820a..212e7093 100644
--- a/utils.py
+++ b/utils.py
@@ -473,6 +473,8 @@ def isReplyToBlogPost(baseDir: str, nickname: str, domain: str,
         return False
     if not postJsonObject['object'].get('inReplyTo'):
         return False
+    if not isinstance(postJsonObject['object']['inReplyTo'], str):
+        return False
     blogsIndexFilename = baseDir + '/accounts/' + \
         nickname + '@' + domain + '/tlblogs.index'
     if not os.path.isfile(blogsIndexFilename):