diff --git a/src/fibRoute.ts b/src/fibRoute.ts
index e4fa96e..c422c6c 100644
--- a/src/fibRoute.ts
+++ b/src/fibRoute.ts
@@ -1,16 +1,18 @@
 // Endpoint for querying the fibonacci numbers
-
+import { Request, Response } from "express";
 import fibonacci from "./fib";
 
-export default (req, res) => {
-  const { num } = req.params;
+export default (req: Request, res: Response): void => {
+    const { num } = req.params;
 
-  const fibN = fibonacci(parseInt(num));
-  let result = `fibonacci(${num}) is ${fibN}`;
+    const parsedNum = parseInt(num, 10);
+    if (isNaN(parsedNum)) {
+        res.send("fibonacci(undefined) is undefined");
+        return;
+    }
 
-  if (fibN < 0) {
-    result = `fibonacci(${num}) is undefined`;
-  }
+    const fibN: number = fibonacci(parsedNum);
+    const result = fibN < 0 ? `fibonacci(${parsedNum}) is undefined` : `fibonacci(${parsedNum}) is ${fibN}`;
 
-  res.send(result);
+    res.send(result);
 };