diff --git a/Optional-Hardening.md b/Optional-Hardening.md
index 43e1250..d9788d7 100644
--- a/Optional-Hardening.md
+++ b/Optional-Hardening.md
@@ -44,6 +44,16 @@ user_pref("extensions.formautofill.creditCards.enabled", false);
 
 ***
 
+### Firefox Strict mode
+Enable [Strict](https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop#w_strict-enhanced-tracking-protection) Enhanced Tracking Protection.
+
+```javascript
+// PREF: enforce ETP Strict
+user_pref("browser.contentblocking.category", "strict");
+```
+
+***
+
 ### Block embedded social posts on webpages
 This matches the default behavior of [Strict](https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop#w_strict-enhanced-tracking-protection) Enhanced Tracking Protection.
 ```javascript