diff --git a/endpoints/registry.py b/endpoints/registry.py
index dc9b31590..7be84d6df 100644
--- a/endpoints/registry.py
+++ b/endpoints/registry.py
@@ -168,6 +168,8 @@ def put_image_checksum(namespace, repository, image_id):
   if err:
     abort(err)
   if checksum not in session.get('checksum', []):
+    logger.debug('session checksums: %s' % session.get('checksum', []))
+    logger.debug('client supplied checksum: %s' % checksum)
     logger.debug('put_image_layer: Wrong checksum')
     abort(400)  #'Checksum mismatch')
   # Checksum is ok, we remove the marker