diff --git a/src/calibre/__init__.py b/src/calibre/__init__.py
index 4a62a5f565..d264168754 100644
--- a/src/calibre/__init__.py
+++ b/src/calibre/__init__.py
@@ -371,20 +371,32 @@ def get_proxy_info(proxy_scheme, proxy_string):
 USER_AGENT = 'Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101210 Gentoo Firefox/3.6.13'
 USER_AGENT_MOBILE = 'Mozilla/5.0 (Windows; U; Windows CE 5.1; rv:1.8.1a3) Gecko/20060610 Minimo/0.016'
 
+
+_ua_list = None
 def random_user_agent(choose=None):
-    choices = [
-        'Mozilla/5.0 (Windows NT 5.2; rv:2.0.1) Gecko/20100101 Firefox/4.0.1',
-        'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1',
-        'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0.1) Gecko/20100101 Firefox/4.0.1',
-        'Mozilla/5.0 (Windows NT 6.1; rv:6.0) Gecko/20110814 Firefox/6.0',
-        'Mozilla/5.0 (Windows NT 6.2; rv:9.0.1) Gecko/20100101 Firefox/9.0.1',
-        'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/534.3 (KHTML, like Gecko) Chrome/6.0.472.63 Safari/534.3',
-        'Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.0.249.78 Safari/532.5',
-        'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)',
-    ]
-    if choose is None:
-        choose = random.randint(0, len(choices)-1)
-    return choices[choose]
+    global _ua_list
+    if _ua_list is None:
+        try:
+            _ua_list = P('common-user-agents.txt', data=True, allow_user_override=False).decode('utf-8').splitlines()
+        except IOError:
+            # People running from source checkout
+            _ua_list =  [
+                 # IE 11 - windows 10
+                 'Mozilla/5.0 (Windows NT 10.0; Trident/7.0; rv:11.0) like Gecko',
+                 # IE 11 - windows 8.1
+                 'Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko',
+                 # IE 11 - windows 8
+                 'Mozilla/5.0 (Windows NT 6.2; Trident/7.0; rv:11.0) like Gecko',
+                 # IE 11 - windows 7
+                 'Mozilla/5.0 (Windows NT 6.1; Trident/7.0; rv:11.0) like Gecko',
+                 # 32bit IE 11 on 64 bit win 10
+                 'Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko',
+                 # 32bit IE 11 on 64 bit win 8.1
+                 'Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko',
+                 # 32bit IE 11 on 64 bit win 7
+                 'Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko',
+            ]
+    return random.choice(_ua_list) if choose is None else _ua_list[choose]
 
 def browser(honor_time=True, max_time=2, mobile_browser=False, user_agent=None, use_robust_parser=False, verify_ssl_certificates=True):
     '''