diff --git a/app/Dockerfile b/app/Dockerfile
index a789219..17677cc 100644
--- a/app/Dockerfile
+++ b/app/Dockerfile
@@ -7,7 +7,6 @@ COPY package.json package-lock.json ./
 RUN npm ci
 
 COPY tsconfig.json ./
-COPY public ./public
 COPY src ./src
 
 RUN npm run build && npm prune --omit=dev
diff --git a/app/package.json b/app/package.json
index 6e595dd..b3c51b3 100644
--- a/app/package.json
+++ b/app/package.json
@@ -3,9 +3,9 @@
   "private": true,
   "type": "module",
   "scripts": {
-    "dev": "tsx watch src/index.ts",
+    "dev": "tsx watch --env-file=.env src/index.ts",
     "build": "tsc",
-    "start": "node dist/index.js"
+    "start": "node --env-file=.env dist/index.js"
   },
   "dependencies": {
     "mqtt": "^5.15.1",
diff --git a/app/src/handlers/edge5-modbus-v2.ts b/app/src/handlers/edge5-modbus-v2.ts
index e5bfaed..7c09ab5 100644
--- a/app/src/handlers/edge5-modbus-v2.ts
+++ b/app/src/handlers/edge5-modbus-v2.ts
@@ -4,12 +4,21 @@ import type { TopicHandler } from '../types.js'
 
 export const TOPIC = 'data/edge5/modbus/v2'
 
+const REGISTER_COUNT = 125
 const mapper = createMetricMapper({
   filePath: process.env.EDGE5_MODBUS_V2_MAPPING_FILE as string,
 })
 
 function parseValues(payload: Buffer): number[] {
-  return JSON.parse(payload.toString('utf8')) as number[]
+  const values = JSON.parse(payload.toString('utf8')) as number[]
+  assertRegisterCount(values)
+  return values
+}
+
+function assertRegisterCount(values: number[]): void {
+  if (values.length !== REGISTER_COUNT) {
+    throw new Error(`Expected ${REGISTER_COUNT} modbus values, got ${values.length}`)
+  }
 }
 
 async function postMetrics(metrics: MappedMetric[]): Promise<void> {
diff --git a/app/src/handlers/edge5-modbus.ts b/app/src/handlers/edge5-modbus.ts
index 7b6b25f..59cfefd 100644
--- a/app/src/handlers/edge5-modbus.ts
+++ b/app/src/handlers/edge5-modbus.ts
@@ -4,6 +4,7 @@ import type { TopicHandler } from '../types.js'
 export const TOPIC = 'data/edge5/modbus/v1'
 
 const EDGE = 'edge5'
+const REGISTER_COUNT = 125
 
 type Edge5ModbusMetric = {
   edge: string
@@ -13,7 +14,15 @@ type Edge5ModbusMetric = {
 }
 
 function parseValues(payload: Buffer): number[] {
-  return JSON.parse(payload.toString('utf8')) as number[]
+  const values = JSON.parse(payload.toString('utf8')) as number[]
+  assertRegisterCount(values)
+  return values
+}
+
+function assertRegisterCount(values: number[]): void {
+  if (values.length !== REGISTER_COUNT) {
+    throw new Error(`Expected ${REGISTER_COUNT} modbus values, got ${values.length}`)
+  }
 }
 
 function toMetrics(values: number[], timestamp: number): Edge5ModbusMetric[] {