diff --git a/schemas/legacy.json b/schemas/legacy.json
index e30beef..f22b271 100644
--- a/schemas/legacy.json
+++ b/schemas/legacy.json
@@ -1116,7 +1116,9 @@
                 "type": ["number", "array"]
             },
             "Pwm": {
-                "type": "number"
+                "type": "number",
+                "minimum": 0,
+                "multipleOf": 1
             },
             "QMax": {
                 "type": "number"