diff --git a/test/md-test.ts b/test/md-test.ts
index 14e014c5..04acba8c 100644
--- a/test/md-test.ts
+++ b/test/md-test.ts
@@ -189,6 +189,9 @@ function run(name: string): void {
       input = input.replace(/\\n/g, '\n');
       input = input.replace(/\\t/g, '\t');
       input = input.replace(/\\f/g, '\f');
+      input = input.replace(/\\x([0-9a-fA-F]+)/g, (all, hex) => {
+        return String.fromCharCode(parseInt(hex, 16));
+      });
 
       // Useful in token tests
       input = input.replace(/\\([0-7]{1,3})/g, (_, digits) => {
diff --git a/test/request/sample.md b/test/request/sample.md
index 1367f9ee..184255a7 100644
--- a/test/request/sample.md
+++ b/test/request/sample.md
@@ -355,6 +355,30 @@ off=37 headers complete method=1 v=1/1 flags=0 content_length=0
 off=37 message complete
 ```
 
+## 255 ASCII in header value
+
+Note: `Buffer.from([ 0xff ]).toString('latin1') === 'ÿ'`.
+
+<!-- meta={"type": "request", "noScan": true} -->
+```http
+OPTIONS /url HTTP/1.1
+Header1: Value1
+Header2: \xffValue2
+
+
+```
+
+```log
+off=0 message begin
+off=8 len=4 span[url]="/url"
+off=23 len=7 span[header_field]="Header1"
+off=32 len=6 span[header_value]="Value1"
+off=40 len=7 span[header_field]="Header2"
+off=49 len=8 span[header_value]="ÿValue2"
+off=61 headers complete method=6 v=1/1 flags=0 content_length=0
+off=61 message complete
+```
+
 ## X-SSL-Nonsense
 
 See nodejs/test/parallel/test-http-headers-obstext.js