diff --git a/mastodon_email_bridge/mastodon_email_bridge.py b/mastodon_email_bridge/mastodon_email_bridge.py
index 940ccf3..6ae4c94 100755
--- a/mastodon_email_bridge/mastodon_email_bridge.py
+++ b/mastodon_email_bridge/mastodon_email_bridge.py
@@ -179,7 +179,10 @@ class MastodonEmailBridge:
             )
             return data
         new_data = data
-        if 'language' not in data:
+        if (
+            'language' not in data or
+            data['language'] is None
+        ):
             source_language = 'auto'
         else:
             source_language = data['language']