diff --git a/TWLight/users/helpers/editor_data.py b/TWLight/users/helpers/editor_data.py
index ea3fc4878a..4b65325e32 100644
--- a/TWLight/users/helpers/editor_data.py
+++ b/TWLight/users/helpers/editor_data.py
@@ -10,6 +10,16 @@
 
 logger = logging.getLogger(__name__)
 
+# Wikimedia's User-Agent policy requires a descriptive User-Agent with contact
+# information; the generic Python-urllib default is blocked with HTTP 403.
+# https://meta.wikimedia.org/wiki/User-Agent_policy
+# The environment (local/staging/production) is included so Wikimedia can
+# distinguish development and staging traffic from production.
+TWLIGHT_USER_AGENT = "TWLight/1.0 ({env}; https://wikipedialibrary.wmflabs.org/; {contact}) Python-urllib".format(
+    env=settings.TWLIGHT_ENV or "unknown",
+    contact=os.environ.get("TWLIGHT_ERROR_MAILTO", "wikipedialibrary@wikimedia.org"),
+)
+
 
 def editor_global_userinfo(wp_sub: int):
     """
@@ -63,7 +73,8 @@ def _get_user_info_request(wp_param_name: str, wp_param: str):
     query = "{endpoint}?action=query&meta=globaluserinfo&{wp_param_name}={wp_param}&guiprop=editcount|merged&format=json&formatversion=2".format(
         endpoint=endpoint, wp_param_name=wp_param_name, wp_param=wp_param
     )
-    return json.loads(urllib.request.urlopen(query).read())
+    request = urllib.request.Request(query, headers={"User-Agent": TWLIGHT_USER_AGENT})
+    return json.loads(urllib.request.urlopen(request).read())
 
 
 def editor_reg_date(identity: dict, global_userinfo: dict):