diff --git a/conf/firefox-forbidden-policies.js b/conf/firefox-forbidden-policies.js
index 86bdcc74..16a40c94 100644
--- a/conf/firefox-forbidden-policies.js
+++ b/conf/firefox-forbidden-policies.js
@@ -86,5 +86,8 @@ lockPref("sidebar.revamp", true);
 lockPref("sidebar.verticalTabs", true);
 lockPref("sidebar.visibility", "always-show");
 
+// Per process isolation
+lockPref("fission.autostart", true);
+
 // 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 52331147..c914e704 100644
--- a/etc/firefox/policies/policies.json
+++ b/etc/firefox/policies/policies.json
@@ -747,6 +747,12 @@
 				"Type": "string",
 				"Value": ""
 			},
+			"fission.autostart": {
+				"Comment": "Enable fission, site separation per process, security. Preference not allowed for stability reasons. :(",
+				"Status": "locked",
+				"Type": "boolean",
+				"Value": true
+			},
 			"general.config.obscure_value": {
 				"Comment": "Required for autoconfig.",
 				"Status": "locked",
@@ -770,6 +776,12 @@
 				"Type": "boolean",
 				"Value": false
 			},
+			"gfx.webrender.all": {
+				"Comment": "Enable fission, site separation per process, security",
+				"Status": "locked",
+				"Type": "boolean",
+				"Value": true
+			},
 			"image.animation.mode": {
 				"Comment": "Preference not allowed for stability reasons. :(",
 				"Status": "default",