diff --git a/slixmpp_omemo/__init__.py b/slixmpp_omemo/__init__.py
index 55e9293..03f803d 100644
--- a/slixmpp_omemo/__init__.py
+++ b/slixmpp_omemo/__init__.py
@@ -549,8 +549,16 @@ class XEP_0384(BasePlugin):
 
         length = await self._omemo().receiving_chain_length(jid.bare, device_id)
         inactive_session = (length or 0) > self.heartbeat_after
+        log.debug(
+            'Chain length for %r / %d: %d -> inactive_session? %r',
+            jid, device_id, length, inactive_session,
+        )
+        log.debug('Is this a prekey message: %r', prekey)
 
-        return prekey or inactive_session
+        res = prekey or inactive_session
+        log.debug('Should heartbeat? %r', res)
+
+        return res
 
     async def should_heartbeat(self, jid: JID, msg: Union[Message, Encrypted]) -> bool:
         """