diff --git a/README.md b/README.md
index 1e929fdc..ee39e7fe 100644
--- a/README.md
+++ b/README.md
@@ -336,6 +336,7 @@ Standardize function and method names in all modules to `to_as1`, `from_as`, etc
   * `Bluesky.get_activities`: skip unknown record types instead of raising `ValueError`.
 * `microformats2`:
   * `object_to_json`: Improve handling of items with multiple types by removing `inReplyTo` from likes, shares, etc ([snarfed/bridgy-fed#941](https://github.com/snarfed/bridgy-fed/issues/941)).
+  * `to_as1`: don't crash on integer UNIX timestamps in `published` and `updated`.
 * `rss`:
   * Support image enclosures, both directions.
   * `from_as1`:
diff --git a/granary/microformats2.py b/granary/microformats2.py
index 4eff5c97..7af1a1ee 100644
--- a/granary/microformats2.py
+++ b/granary/microformats2.py
@@ -171,7 +171,7 @@ def maybe_normalize_iso8601(val):
   val = get_text(val)
   try:
     return dateutil.parser.parse(val).isoformat()
-  except ValueError as e:
+  except (OverflowError, ValueError) as e:
     logger.debug(e)
     return val
 
diff --git a/granary/tests/test_microformats2.py b/granary/tests/test_microformats2.py
index 0a5f5d6d..4ad0b02f 100644
--- a/granary/tests/test_microformats2.py
+++ b/granary/tests/test_microformats2.py
@@ -1012,6 +1012,18 @@ def test_to_as1_rel_urls_actor_urls_text_title_one_url(self):
       },
     }))
 
+  def test_to_as1_bad_timestamps(self):
+    for bad in ('*', '1735561920000', 'foo'):
+      self.assert_equals({
+        'objectType': 'note',
+        'published': bad,
+      }, microformats2.to_as1({
+        'type': ['h-entry'],
+        'properties': {
+          'published': [bad],
+        },
+      }))
+
   def test_hfeed_to_as1(self):
     self.assert_equals([{
       'objectType': 'activity',