diff --git a/browsers.json b/browsers.json
index 4677f19866..5e7a9b6e79 100644
--- a/browsers.json
+++ b/browsers.json
@@ -13,7 +13,7 @@
     },
     {
       "name": "firefox",
-      "revision": "1294",
+      "revision": "1295",
       "installByDefault": true
     },
     {
diff --git a/src/server/firefox/protocol.d.ts b/src/server/firefox/protocol.d.ts
index 05c22bbe7a..b8f506ec29 100644
--- a/src/server/firefox/protocol.d.ts
+++ b/src/server/firefox/protocol.d.ts
@@ -908,6 +908,7 @@ export module Protocol {
       requestId: string;
       responseEndTime: number;
       transferSize: number;
+      encodedBodySize: number;
       protocolVersion: string;
     }
     export type requestFailedPayload = {