diff --git a/lib/headless-browser.js b/lib/headless-browser.js
index 46f6a02..2664583 100644
--- a/lib/headless-browser.js
+++ b/lib/headless-browser.js
@@ -464,7 +464,9 @@ class HeadlessBrowser {
         }
 
         return {
-            data: screenshotBuffer.toString('base64'),
+            // Puppeteer >=22 returns Uint8Array, whose toString() ignores the
+            // 'base64' argument — wrap in Buffer so encoding applies.
+            data: Buffer.from(screenshotBuffer).toString('base64'),
             mimeType: 'image/jpeg'
         };
     }