diff --git a/requirements.txt b/requirements.txt
index 445c20b..a7f611f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,18 +1,19 @@
 # Add here external Python modules dependencies, one per line. Module names
 # should match https://pypi.python.org/pypi names. For the full spec or
 # dependency lines, see https://pip.readthedocs.org/en/1.1/requirements.html
 vcversioner
 
 # remote storage API client
 requests
 
 # remote storage API server
 flask
 
 # Internal dependencies
 swh.core >= 0.0.20
 swh.storage.archiver >= 0.0.52
 click
 
-apache-libcloud
-azure-storage
+# optional dependencies
+# apache-libcloud
+# azure-storage