diff --git a/scripts/config/firefox/mozilla.cfg b/scripts/config/firefox/mozilla.cfg
index 519d33e..64044ed 100644
--- a/scripts/config/firefox/mozilla.cfg
+++ b/scripts/config/firefox/mozilla.cfg
@@ -73,4 +73,5 @@ defaultPref("toolkit.telemetry.pioneer-new-studies-available", false);
 defaultPref("toolkit.telemetry.reportingpolicy.firstRun", false);
 defaultPref("trailhead.firstrun.didSeeAboutWelcome", true);
 defaultPref("network.proxy.type", 0);
+lockPref("security.mixed_content.block_display_content", true);