diff --git a/src/calibre/utils/random_ua.py b/src/calibre/utils/random_ua.py
index 8fbc003bf5..6dcf7b7890 100644
--- a/src/calibre/utils/random_ua.py
+++ b/src/calibre/utils/random_ua.py
@@ -20,7 +20,7 @@ def common_user_agents():
     return user_agent_data()['common_user_agents']
 
 
-def all_firefox_versions(limit=7):
+def all_firefox_versions(limit=10):
     return user_agent_data()['firefox_versions'][:limit]
 
 
@@ -42,7 +42,7 @@ def random_firefox_ua():
     render_firefox_ua(random_desktop_platform(), random_firefox_version())
 
 
-def all_chrome_versions(limit=7):
+def all_chrome_versions(limit=10):
     return user_agent_data()['chrome_versions'][:limit]