diff --git a/tree/30_generic_methods/file_from_shared_folder.cf b/tree/30_generic_methods/file_from_shared_folder.cf
index da0c528c1..18ad09814 100644
--- a/tree/30_generic_methods/file_from_shared_folder.cf
+++ b/tree/30_generic_methods/file_from_shared_folder.cf
@@ -21,7 +21,8 @@
 #
 # @parameter source      Source file (path relative to Rudder shared folder)
 # @parameter destination Destination file (absolute path on the target node)
-# @parameter hash_type   Hash algorithm used to check if file is updated
+# @parameter hash_type   Hash algorithm used to check if file is updated (md5, sha1, sha256), only md5 can be used on cfengine agent
+# @parameter_constraint hash_type  "select" : [ "md5", "sha1", "sha256" ]
 # 
 # @class_prefix file_from_shared_folder
 # @class_parameter destination