diff --git a/conf/firefox-forbidden-policies.js b/conf/firefox-forbidden-policies.js
index d81fb5c3..575a3496 100644
--- a/conf/firefox-forbidden-policies.js
+++ b/conf/firefox-forbidden-policies.js
@@ -125,6 +125,8 @@ lockPref("security.ssl.enable_ocsp_must_staple", true);
 
 // New sidebar
 lockPref("sidebar.revamp", true);
+lockPref("sidebar.verticalTabs", true);
+lockPref("sidebar.visibility", "always-show");
 
 // No making configuration on the last line of the file!
 //
diff --git a/etc/firefox/policies/policies.json b/etc/firefox/policies/policies.json
index eb904685..ca3defb6 100644
--- a/etc/firefox/policies/policies.json
+++ b/etc/firefox/policies/policies.json
@@ -961,6 +961,18 @@
 				"Type": "boolean",
 				"Value": true
 			},
+			"sidebar.verticalTabs": {
+				"Comment": "Preference not allowed for stability reasons.",
+				"Status": "locked",
+				"Type": "boolean",
+				"Value": true
+			},
+			"sidebar.visibility": {
+				"Comment": "Preference not allowed for stability reasons.",
+				"Status": "locked",
+				"Type": "boolean",
+				"Value": "always-show"
+			},
 			"ui.systemUsesDarkTheme": {
 				"Comment": "Another defaulting to dark theme.",
 				"Status": "clear",