diff --git a/src/main/ua-parser.js b/src/main/ua-parser.js
index 7978902..8730b63 100755
--- a/src/main/ua-parser.js
+++ b/src/main/ua-parser.js
@@ -1236,14 +1236,21 @@
             headers = extensions;                       // case UAParser(ua, headers)
             extensions = undefined;
         }
+
+        // Convert Headers object into a plain object
+        if (headers && typeof headers.append === FUNC_TYPE) {
+            var kv = {};
+            headers.forEach(function (v, k) { kv[k] = v; });
+            headers = kv;
+        }
         
         if (!(this instanceof UAParser)) {
             return new UAParser(ua, extensions, headers).getResult();
         }
 
         var userAgent = typeof ua === STR_TYPE ? ua :                                       // Passed user-agent string
-                            ((NAVIGATOR && NAVIGATOR.userAgent) ? NAVIGATOR.userAgent :     // navigator.userAgent
                                 (headers && headers[USER_AGENT] ? headers[USER_AGENT] :     // User-Agent from passed headers
+                                ((NAVIGATOR && NAVIGATOR.userAgent) ? NAVIGATOR.userAgent : // navigator.userAgent
                                     EMPTY)),                                                // empty string
 
             httpUACH = new UACHData(headers, true),
diff --git a/test/playwright-test-main.spec.mjs b/test/playwright-test-main.spec.mjs
index fe4ac7c..db6e149 100644
--- a/test/playwright-test-main.spec.mjs
+++ b/test/playwright-test-main.spec.mjs
@@ -123,4 +123,21 @@ test.describe('withFeatureCheck() tests', () => {
         expect(uap).toHaveProperty('device.model', 'iPad');
         expect(uap).toHaveProperty('device.type', 'tablet');
     });
-});
\ No newline at end of file
+});
+
+test.describe('request.headers can be passed in form of a Headers object', () => {
+
+    test('Headers automatically converted into a plain key-value object', async ({ page }) => {
+        await page.addInitScript(() => {
+            Object.defineProperty(window, 'req', {
+                value : {
+                    headers: new Headers([["User-Agent", "myBrowser/1.0"]])
+                }
+            });
+        });
+        await page.goto(localHtml);
+        // @ts-ignore
+        const uap = await page.evaluate(() => UAParser(req.headers));
+        expect(uap.ua).toBe('myBrowser/1.0');
+    });
+});