--- a/src/pyams_utils/adapter.py	Wed Jun 13 11:24:18 2018 +0200
+++ b/src/pyams_utils/adapter.py	Wed Jun 13 11:25:38 2018 +0200
@@ -159,6 +159,8 @@
         else:
             adapter = annotations[key] = factory()
             if markers:
+                if not isinstance(markers, (list, tuple, set)):
+                    markers = {markers}
                 for marker in markers:
                     alsoProvides(adapter, marker)
             if notify: