diff --git a/lib/NetworkManager.js b/lib/NetworkManager.js
index ed85edffc85..66daac4a3fb 100644
--- a/lib/NetworkManager.js
+++ b/lib/NetworkManager.js
@@ -571,10 +571,12 @@ function generateRequestHash(request) {
   if (!normalizedURL.startsWith('data:')) {
     const headers = Object.keys(request.headers);
     headers.sort();
-    for (const header of headers) {
-      if (header === 'Accept' || header === 'Referer' || header === 'X-DevTools-Emulate-Network-Conditions-Client-Id')
+    for (let header of headers) {
+      const headerValue = request.headers[header];
+      header = header.toLowerCase();
+      if (header === 'accept' || header === 'referer' || header === 'x-devtools-emulate-network-conditions-client-id')
         continue;
-      hash.headers[header] = request.headers[header];
+      hash.headers[header] = headerValue;
     }
   }
   return JSON.stringify(hash);
diff --git a/test/test.js b/test/test.js
index 3bd62ff8ab8..c06accd8242 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1332,6 +1332,16 @@ describe('Page', function() {
       const response = await page.goto(server.EMPTY_PAGE);
       expect(response.ok()).toBe(true);
     });
+    it('should works with customizing referer headers', async({page, server}) => {
+      await page.setExtraHTTPHeaders({ 'referer': server.EMPTY_PAGE });
+      await page.setRequestInterception(true);
+      page.on('request', request => {
+        expect(request.headers()['referer']).toBe(server.EMPTY_PAGE);
+        request.continue();
+      });
+      const response = await page.goto(server.EMPTY_PAGE);
+      expect(response.ok()).toBe(true);
+    });
     it('should be abortable', async({page, server}) => {
       await page.setRequestInterception(true);
       page.on('request', request => {