diff --git a/schemas/legacy.json b/schemas/legacy.json
index b251c8a..be634dc 100644
--- a/schemas/legacy.json
+++ b/schemas/legacy.json
@@ -860,7 +860,7 @@
                 "type": "number"
             },
             "SensorType": {
-                "type": "string"
+                "enum": ["current", "power", "voltage"]
             },
             "SlotId": {
                 "type": "string"