diff --git a/atom/browser/atom_browser_client.cc b/atom/browser/atom_browser_client.cc
index 827dbe4e159c..4a5d2d968bed 100644
--- a/atom/browser/atom_browser_client.cc
+++ b/atom/browser/atom_browser_client.cc
@@ -87,8 +87,8 @@ void AtomBrowserClient::OverrideWebkitPrefs(
   prefs->allow_universal_access_from_file_urls = true;
   prefs->allow_file_access_from_file_urls = true;
   prefs->experimental_webgl_enabled = true;
-  prefs->allow_displaying_insecure_content = true;
-  prefs->allow_running_insecure_content = true;
+  prefs->allow_displaying_insecure_content = false;
+  prefs->allow_running_insecure_content = false;
 
   // Turn off web security for devtools.
   if (url.SchemeIs("chrome-devtools")) {