diff --git a/packages/large-response-middleware/src/index.ts b/packages/large-response-middleware/src/index.ts
index efc3f16..c0242d6 100644
--- a/packages/large-response-middleware/src/index.ts
+++ b/packages/large-response-middleware/src/index.ts
@@ -60,7 +60,7 @@ export const withLargeResponseHandler = ({
           : '';
         const payload = (handlerRequestContext?.response?.body ?? '') + responseHeadersString;
 
-        const aproxContentLengthBytes = payload.length * 1.0;
+        const aproxContentLengthBytes = Buffer.byteLength(payload, 'utf8');
         const contentLengthMB = aproxContentLengthBytes > 0 ? aproxContentLengthBytes / TO_MB_FACTOR : 0.0;
         const sizeLimitInMB = (_sizeLimitInMB ?? LIMIT_REQUEST_SIZE_MB) * 1.0;
         const thresholdWarnInMB = (thresholdWarn ?? 0.0) * 1.0 * sizeLimitInMB;
diff --git a/packages/large-response-middleware/tsconfig.json b/packages/large-response-middleware/tsconfig.json
index 74e6b1c..d612497 100644
--- a/packages/large-response-middleware/tsconfig.json
+++ b/packages/large-response-middleware/tsconfig.json
@@ -6,7 +6,7 @@
     "moduleResolution": "node",
     "lib": ["ESNext"],
     "sourceMap": true,
-    "types": ["vitest/globals"],
+    "types": ["vitest/globals", "node"],
     "strict": true,
     "strictFunctionTypes": true,
     "noImplicitReturns": true,