diff --git a/src/env.ts b/src/env.ts
index 721f4ff..b3312f1 100644
--- a/src/env.ts
+++ b/src/env.ts
@@ -1,6 +1,72 @@
-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 headersTimeoutValue = process.env['HEADERS_TIMEOUT'];
+const requestTimeoutValue = process.env['REQUEST_TIMEOUT'];
+const keepAliveTimeoutValue = process.env['KEEP_ALIVE_TIMEOUT'];
+const maxDelayValue = process.env['MAX_DELAY'];
+const portValue = process.env['PORT'];
+
+// Convert environment variables with error handling
+const headersTimeout =
+  headersTimeoutValue !== undefined
+    ? (() => {
+        const parsed = toSafeInteger(headersTimeoutValue);
+        if (parsed === undefined) {
+          throw new Error(
+            `Invalid HEADERS_TIMEOUT value: "${headersTimeoutValue}". Must be a valid integer.`
+          );
+        }
+        return parsed;
+      })()
+    : 10000;
+
+const requestTimeout =
+  requestTimeoutValue !== undefined
+    ? (() => {
+        const parsed = toSafeInteger(requestTimeoutValue);
+        if (parsed === undefined) {
+          throw new Error(
+            `Invalid REQUEST_TIMEOUT value: "${requestTimeoutValue}". Must be a valid integer.`
+          );
+        }
+        return parsed;
+      })()
+    : 30000;
+
+const keepAliveTimeout =
+  keepAliveTimeoutValue !== undefined
+    ? (() => {
+        const parsed = toSafeInteger(keepAliveTimeoutValue);
+        if (parsed === undefined) {
+          throw new Error(
+            `Invalid KEEP_ALIVE_TIMEOUT value: "${keepAliveTimeoutValue}". Must be a valid integer.`
+          );
+        }
+        return parsed;
+      })()
+    : 5000;
+
+const maxDelay =
+  maxDelayValue !== undefined
+    ? (() => {
+        const parsed = toSafeInteger(maxDelayValue);
+        if (parsed === undefined) {
+          throw new Error(`Invalid MAX_DELAY value: "${maxDelayValue}". Must be a valid integer.`);
+        }
+        return parsed;
+      })()
+    : 10000;
+
+const port =
+  portValue !== undefined
+    ? (() => {
+        const parsed = toSafeInteger(portValue);
+        if (parsed === undefined) {
+          throw new Error(`Invalid PORT value: "${portValue}". Must be a valid integer.`);
+        }
+        return parsed;
+      })()
+    : 8000;
 
 if (headersTimeout <= keepAliveTimeout) {
   throw new Error(
@@ -19,9 +85,9 @@ export const environment = {
   headersTimeout,
   keepAliveTimeout,
   logLevel: process.env['LOG_LEVEL'] || 'info',
-  maxDelay: Number(process.env['MAX_DELAY']) || 10000,
+  maxDelay,
   nodeEnv: process.env['NODE_ENV'] || 'development',
   origin: process.env['ORIGIN'] || '*',
-  port: Number(process.env['PORT']) || 8000,
+  port,
   requestTimeout,
 };
diff --git a/tests/ut/env.test.ts b/tests/ut/env.test.ts
index 80ee025..5c1f205 100644
--- a/tests/ut/env.test.ts
+++ b/tests/ut/env.test.ts
@@ -80,4 +80,54 @@ describe('Environment configuration', () => {
       requestTimeout: 40000,
     });
   });
+
+  describe('Invalid environment variable values', () => {
+    it('should throw an error for invalid HEADERS_TIMEOUT value', async () => {
+      process.env.HEADERS_TIMEOUT = 'invalid';
+
+      await expect(loadEnv()).rejects.toThrow(
+        'Invalid HEADERS_TIMEOUT value: "invalid". Must be a valid integer.'
+      );
+    });
+
+    it('should throw an error for invalid REQUEST_TIMEOUT value', async () => {
+      process.env.REQUEST_TIMEOUT = '12.5';
+
+      await expect(loadEnv()).rejects.toThrow(
+        'Invalid REQUEST_TIMEOUT value: "12.5". Must be a valid integer.'
+      );
+    });
+
+    it('should throw an error for invalid KEEP_ALIVE_TIMEOUT value', async () => {
+      process.env.KEEP_ALIVE_TIMEOUT = 'abc123';
+
+      await expect(loadEnv()).rejects.toThrow(
+        'Invalid KEEP_ALIVE_TIMEOUT value: "abc123". Must be a valid integer.'
+      );
+    });
+
+    it('should throw an error for invalid MAX_DELAY value', async () => {
+      process.env.MAX_DELAY = '1e5';
+
+      await expect(loadEnv()).rejects.toThrow(
+        'Invalid MAX_DELAY value: "1e5". Must be a valid integer.'
+      );
+    });
+
+    it('should throw an error for invalid PORT value', async () => {
+      process.env.PORT = 'port8000';
+
+      await expect(loadEnv()).rejects.toThrow(
+        'Invalid PORT value: "port8000". Must be a valid integer.'
+      );
+    });
+
+    it('should throw an error for out-of-safe-range values', async () => {
+      process.env.PORT = '9007199254740992'; // Number.MAX_SAFE_INTEGER + 1
+
+      await expect(loadEnv()).rejects.toThrow(
+        'Invalid PORT value: "9007199254740992". Must be a valid integer.'
+      );
+    });
+  });
 });