diff --git a/json/schemas/whitelabel-schema.json b/json/schemas/whitelabel-schema.json
index a9444b1..2dbefe3 100644
--- a/json/schemas/whitelabel-schema.json
+++ b/json/schemas/whitelabel-schema.json
@@ -49,15 +49,20 @@
                     "description": "Max power consumption, in 2mA units",
                     "type": ["integer", "string"],
                     "maximum": 255,
-                    "pattern": "^0x[0-9a-fA-F]{0,2}$"
+                    "pattern": "^0x[0-9a-fA-F]{1,2}$"
                 },
                 "attributes": {
                     "description": "Device attributes: bit 7 must be 1, bit 6 is self-powered, bit 5 is remote wakeup, bits 0-4 must be 0",
                     "type": ["integer", "string"],
-                    "maximum": 255,
-                    "pattern": "^0x[0-9a-fA-F]{0,2}$"
+                    "minimum": 128,
+                    "maximum": 224,
+                    "pattern": "^0x[0-9a-fA-F]{2}$"
                 }
             },
+            "dependentRequired": {
+                "max_power": ["attributes"],
+                "attributes": ["max_power"]
+            },
             "additionalProperties": false
         },
         "scsi": {
diff --git a/main.cpp b/main.cpp
index 0bc722d..d1e43c2 100644
--- a/main.cpp
+++ b/main.cpp
@@ -7278,19 +7278,20 @@ bool otp_white_label_command::execute(device_map &devices) {
         // Check for separate max_power and attributes
         uint16_t val = 0;
         int hex_val = 0;
-        if (wl_json["device"].contains("max_power")) {
+        if (wl_json["device"].contains("max_power") && wl_json["device"].contains("attributes")) {
             if (!get_json_int(wl_json["device"]["max_power"], hex_val)) {
                 fail(ERROR_FORMAT, "MaxPower must be an integer");
             }
             val |= (hex_val << 8);
-        }
-        if (wl_json["device"].contains("attributes")) {
+
             if (!get_json_int(wl_json["device"]["attributes"], hex_val)) {
                 fail(ERROR_FORMAT, "Device Attributes must be an integer");
             } else if (hex_val & 0b11111 || ~hex_val & 0x80) {
                 fail(ERROR_FORMAT, "Device Attributes must have bit 7 set (0x80), and bits 4-0 clear");
             }
             val |= hex_val;
+        } else if (wl_json["device"].contains("max_power") || wl_json["device"].contains("attributes")) {
+            fail(ERROR_INCOMPATIBLE, "Must specify both max_power and attributes in the JSON file");
         }
         if (val) {
             fos << "Setting attributes " << hex_string(val, 4) << "\n";