diff --git a/tuf/client/updater.py b/tuf/client/updater.py
index b974a5f919..1eace2e5c7 100755
--- a/tuf/client/updater.py
+++ b/tuf/client/updater.py
@@ -693,6 +693,9 @@ def __init__(self, repository_name, repository_mirrors,
         If there is an error with the updater's repository files, such
         as a missing 'root.json' file.
 
+    tuf.exceptions.Error:
+      If the targets map file cannot be loaded.
+
     <Side Effects>
       Th metadata files (e.g., 'root.json', 'targets.json') for the top- level
       roles are read from disk and stored in dictionaries.  In addition, the