diff --git a/schemas/legacy.json b/schemas/legacy.json
index 6e5a93b..6fd6ba3 100644
--- a/schemas/legacy.json
+++ b/schemas/legacy.json
@@ -677,7 +677,9 @@
                             "type": "string"
                         },
                         "Severity": {
-                            "type": "number"
+                            "type": "number",
+                            "minimum": 0,
+                            "maximum": 4
                         },
                         "Value": {
                             "type": "number"