diff --git a/anki/consts.py b/anki/consts.py
index e2427a16b..77651e478 100644
--- a/anki/consts.py
+++ b/anki/consts.py
@@ -44,6 +44,7 @@ MODEL_CLOZE = 1
 # deck schema & syncing vars
 SCHEMA_VERSION = 11
 SYNC_ZIP_SIZE = int(2.5*1024*1024)
+SYNC_ZIP_COUNT = 300
 SYNC_URL = os.environ.get("SYNC_URL") or "https://ankiweb.net/sync/"
 SYNC_VER = 5
 
diff --git a/anki/media.py b/anki/media.py
index 09676da9f..2fda0d652 100644
--- a/anki/media.py
+++ b/anki/media.py
@@ -310,7 +310,7 @@ If the same name exists, compare checksums."""
     # and place a json file in the zip with the necessary information.
 
     def zipAdded(self):
-        "Add files to a zip until over SYNC_ZIP_SIZE. Return zip data."
+        "Add files to a zip until over SYNC_ZIP_SIZE/COUNT. Return zip data."
         f = StringIO()
         z = zipfile.ZipFile(f, "w", compression=zipfile.ZIP_DEFLATED)
         sz = 0
@@ -330,7 +330,7 @@ If the same name exists, compare checksums."""
             z.write(fname, str(cnt))
             files[str(cnt)] = fname
             sz += os.path.getsize(fname)
-            if sz > SYNC_ZIP_SIZE:
+            if sz > SYNC_ZIP_SIZE or cnt > SYNC_ZIP_COUNT:
                 break
             cnt += 1
         z.writestr("_meta", json.dumps(files))