diff --git a/mautrix_telegram/portal.py b/mautrix_telegram/portal.py
index cc40cc7a..00a79d5b 100644
--- a/mautrix_telegram/portal.py
+++ b/mautrix_telegram/portal.py
@@ -3628,7 +3628,9 @@ class Portal(DBPortal, BasePortal):
     async def _mark_disappearing(
         self, event_id: EventID, seconds: int, expires_at: int | None
     ) -> None:
-        dm = DisappearingMessage(self.mxid, event_id, seconds, expiration_ts=expires_at * 1000)
+        dm = DisappearingMessage(
+            self.mxid, event_id, seconds, expiration_ts=expires_at * 1000 if expires_at else None
+        )
         await dm.insert()
         if expires_at:
             background_task.create(self._disappear_event(dm))
diff --git a/mautrix_telegram/portal_util/message_convert.py b/mautrix_telegram/portal_util/message_convert.py
index a195a2a0..6494df7e 100644
--- a/mautrix_telegram/portal_util/message_convert.py
+++ b/mautrix_telegram/portal_util/message_convert.py
@@ -439,9 +439,21 @@ class TelegramMessageConverter:
         return ConvertedMessage(
             content=content,
             caption=caption_content,
-            disappear_seconds=media.ttl_seconds,
+            disappear_seconds=self._adjust_ttl(media.ttl_seconds),
         )
 
+    @staticmethod
+    def _adjust_ttl(ttl: int | None) -> int | None:
+        if not ttl:
+            return None
+        elif ttl == 2147483647:
+            # View-once media, set low TTL
+            return 15
+        else:
+            # Increase media TTL because it's supposed to be counted from opening the media,
+            # but we can only count it from read receipt.
+            return ttl * 5
+
     async def _convert_document(
         self,
         source: au.AbstractUser,
@@ -548,7 +560,7 @@ class TelegramMessageConverter:
             type=event_type,
             content=content,
             caption=caption_content,
-            disappear_seconds=evt.media.ttl_seconds,
+            disappear_seconds=self._adjust_ttl(evt.media.ttl_seconds),
         )
 
     @staticmethod
diff --git a/requirements.txt b/requirements.txt
index 838adb8e..c2e85b9a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@ commonmark>=0.8,<0.10
 aiohttp>=3,<4
 yarl>=1,<2
 mautrix>=0.20.2,<0.21
-tulir-telethon==1.30.0a2
+tulir-telethon==1.32.0a1
 asyncpg>=0.20,<0.29
 mako>=1,<2
 setuptools