diff --git a/server/djrandom/model/mp3.py b/server/djrandom/model/mp3.py
index 13cc5fc5421c842ec99f3ae0367699f077f09530..30cf87f27a6de00dc7cbd88d5f76df0f37294acc 100644
--- a/server/djrandom/model/mp3.py
+++ b/server/djrandom/model/mp3.py
@@ -77,7 +77,7 @@ class MP3(Base):
                 'genre': self.genre,
                 'sha1': self.sha1,
                 'size': self.size,
-                'uploaded_at': self.uploaded_at}
+                'uploaded_at': self.uploaded_at.isoformat()}
         if self.duplicate_of:
             data['duplicate_of'] = self.duplicate_of
         if self.track_num: