diff --git a/changedetectionio/content_fetcher.py b/changedetectionio/content_fetcher.py
index db9e23dc..d7a4f835 100644
--- a/changedetectionio/content_fetcher.py
+++ b/changedetectionio/content_fetcher.py
@@ -343,8 +343,8 @@ class base_html_playwright(Fetcher):
                         'req_headers': request_headers,
                         'screenshot_quality': int(os.getenv("PLAYWRIGHT_SCREENSHOT_QUALITY", 72)),
                         'url': url,
-                        'user_agent': request_headers.get('User-Agent', 'Mozilla/5.0'),
-                        'proxy_username': self.proxy.get('username','') if self.proxy else False,
+                        'user_agent': {k.lower(): v for k, v in request_headers.items()}.get('user-agent', None),
+                        'proxy_username': self.proxy.get('username', '') if self.proxy else False,
                         'proxy_password': self.proxy.get('password', '') if self.proxy else False,
                         'no_cache_list': [
                             'twitter',
@@ -443,7 +443,7 @@ class base_html_playwright(Fetcher):
             # Set user agent to prevent Cloudflare from blocking the browser
             # Use the default one configured in the App.py model that's passed from fetch_site_status.py
             context = browser.new_context(
-                user_agent=request_headers.get('User-Agent', 'Mozilla/5.0'),
+                user_agent={k.lower(): v for k, v in request_headers.items()}.get('user-agent', None),
                 proxy=self.proxy,
                 # This is needed to enable JavaScript execution on GitHub and others
                 bypass_csp=True,
@@ -684,7 +684,7 @@ class html_requests(Fetcher):
             is_binary=False):
 
         # Make requests use a more modern looking user-agent
-        if not 'User-Agent' in request_headers:
+        if not {k.lower(): v for k, v in request_headers.items()}.get('user-agent', None):
             request_headers['User-Agent'] = os.getenv("DEFAULT_SETTINGS_HEADERS_USERAGENT",
                                                       'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.66 Safari/537.36')
 
diff --git a/changedetectionio/res/puppeteer_fetch.js b/changedetectionio/res/puppeteer_fetch.js
index d376729f..6015fbe8 100644
--- a/changedetectionio/res/puppeteer_fetch.js
+++ b/changedetectionio/res/puppeteer_fetch.js
@@ -18,7 +18,9 @@ module.exports = async ({page, context}) => {
 
     await page.setBypassCSP(true)
     await page.setExtraHTTPHeaders(req_headers);
-    await page.setUserAgent(user_agent);
+    if (user_agent) {
+        await page.setUserAgent(user_agent);
+    }
     // https://ourcodeworld.com/articles/read/1106/how-to-solve-puppeteer-timeouterror-navigation-timeout-of-30000-ms-exceeded
 
     await page.setDefaultNavigationTimeout(0);