diff --git a/app/mastodon_account.rb b/app/mastodon_account.rb
index 0852397..02b0420 100644
--- a/app/mastodon_account.rb
+++ b/app/mastodon_account.rb
@@ -12,6 +12,10 @@ class MastodonAccount
     @config = File.exist?(CONFIG_FILE) ? YAML.load(File.read(CONFIG_FILE)) : {}
   end
 
+  def max_alt_length
+    1500
+  end
+
   def save_config
     File.write(CONFIG_FILE, YAML.dump(@config))
   end
diff --git a/app/tootify.rb b/app/tootify.rb
index bbfae87..3c3882a 100644
--- a/app/tootify.rb
+++ b/app/tootify.rb
@@ -106,6 +106,10 @@ class Tootify
         cid = image['image']['ref']['$link']
         mime = image['image']['mimeType']
 
+        if alt.length > @mastodon.max_alt_length
+          alt = alt[0...@mastodon.max_alt_length - 3] + "(…)"
+        end
+
         data = @bluesky.fetch_blob(cid)
 
         uploaded_media = @mastodon.upload_media(data, cid, mime, alt)