diff --git a/src/env.ts b/src/env.ts
index 721f4ff..13010b8 100644
--- a/src/env.ts
+++ b/src/env.ts
@@ -1,6 +1,20 @@
-const headersTimeout = Number(process.env['HEADERS_TIMEOUT']) || 10000;
-const requestTimeout = Number(process.env['REQUEST_TIMEOUT']) || 30000;
-const keepAliveTimeout = Number(process.env['KEEP_ALIVE_TIMEOUT']) || 5000;
+import { toSafeInteger } from './utils/number.js';
+
+const parseEnvInteger = (envVar: string, defaultValue: number): number => {
+  const value = process.env[envVar];
+  if (value === undefined) {
+    return defaultValue;
+  }
+  const parsed = toSafeInteger(value);
+  if (parsed === undefined) {
+    throw new Error(`Invalid ${envVar} environment variable: "${value}" is not a valid integer`);
+  }
+  return parsed;
+};
+
+const headersTimeout = parseEnvInteger('HEADERS_TIMEOUT', 10000);
+const requestTimeout = parseEnvInteger('REQUEST_TIMEOUT', 30000);
+const keepAliveTimeout = parseEnvInteger('KEEP_ALIVE_TIMEOUT', 5000);
 
 if (headersTimeout <= keepAliveTimeout) {
   throw new Error(
@@ -19,9 +33,9 @@ export const environment = {
   headersTimeout,
   keepAliveTimeout,
   logLevel: process.env['LOG_LEVEL'] || 'info',
-  maxDelay: Number(process.env['MAX_DELAY']) || 10000,
+  maxDelay: parseEnvInteger('MAX_DELAY', 10000),
   nodeEnv: process.env['NODE_ENV'] || 'development',
   origin: process.env['ORIGIN'] || '*',
-  port: Number(process.env['PORT']) || 8000,
+  port: parseEnvInteger('PORT', 8000),
   requestTimeout,
 };
diff --git a/tests/ut/env.test.ts b/tests/ut/env.test.ts
index 80ee025..7674858 100644
--- a/tests/ut/env.test.ts
+++ b/tests/ut/env.test.ts
@@ -80,4 +80,52 @@ describe('Environment configuration', () => {
       requestTimeout: 40000,
     });
   });
+
+  it('should throw an error when HEADERS_TIMEOUT is not a valid integer', async () => {
+    process.env.HEADERS_TIMEOUT = 'invalid';
+
+    await expect(loadEnv()).rejects.toThrow(
+      'Invalid HEADERS_TIMEOUT environment variable: "invalid" is not a valid integer'
+    );
+  });
+
+  it('should throw an error when REQUEST_TIMEOUT is not a valid integer', async () => {
+    process.env.REQUEST_TIMEOUT = '1.5';
+
+    await expect(loadEnv()).rejects.toThrow(
+      'Invalid REQUEST_TIMEOUT environment variable: "1.5" is not a valid integer'
+    );
+  });
+
+  it('should throw an error when KEEP_ALIVE_TIMEOUT is not a valid integer', async () => {
+    process.env.KEEP_ALIVE_TIMEOUT = '2e10';
+
+    await expect(loadEnv()).rejects.toThrow(
+      'Invalid KEEP_ALIVE_TIMEOUT environment variable: "2e10" is not a valid integer'
+    );
+  });
+
+  it('should throw an error when MAX_DELAY is not a valid integer', async () => {
+    process.env.MAX_DELAY = 'abc';
+
+    await expect(loadEnv()).rejects.toThrow(
+      'Invalid MAX_DELAY environment variable: "abc" is not a valid integer'
+    );
+  });
+
+  it('should throw an error when PORT is not a valid integer', async () => {
+    process.env.PORT = '8000.0';
+
+    await expect(loadEnv()).rejects.toThrow(
+      'Invalid PORT environment variable: "8000.0" is not a valid integer'
+    );
+  });
+
+  it('should throw an error when integer is out of safe range', async () => {
+    process.env.PORT = '9007199254740992';
+
+    await expect(loadEnv()).rejects.toThrow(
+      'Invalid PORT environment variable: "9007199254740992" is not a valid integer'
+    );
+  });
 });