diff --git a/scripts/msnet-add-id/script.py b/scripts/msnet-add-id/script.py
new file mode 100644
index 0000000..71bd480
--- /dev/null
+++ b/scripts/msnet-add-id/script.py
@@ -0,0 +1,36 @@
+import requests
+
+from inspirehep.curation.search_check_do import SearchCheckDo
+
+URL = (
+    "https://cernbox.cern.ch/remote.php/dav/public-files/"
+    "DgV3O0I8D8haXMZ/msnet_add_id.json"
+)
+MSNET_IDS = requests.get(URL).json()
+
+ELEMENT = "external_system_identifiers"
+
+
+class AddMsnetIds(SearchCheckDo):
+    """Add MSNET IDs to INSPIRE records."""
+
+    query = f"tc:p -{ELEMENT}.schema:MSNET"
+
+    @staticmethod
+    def check(record, logger, state):
+        return record["control_number"] in MSNET_IDS and not any(
+            id_["schema"] == "MSNET"
+            for id_ in record.get("external_system_identifiers", [])
+        )
+
+    @staticmethod
+    def do(record, logger, state):
+        record.setdefault(ELEMENT, []).append(
+            {
+                "value": MSNET_IDS[record.get_value("control_number")],
+                "schema": "MSNET",
+            }
+        )
+
+
+AddMsnetIds()