diff --git a/web/js/MonitorStream.js b/web/js/MonitorStream.js
index 373902e1f..b5f9d0b6a 100644
--- a/web/js/MonitorStream.js
+++ b/web/js/MonitorStream.js
@@ -521,6 +521,9 @@ async function attachVideo(id) {
       if (jsep !== undefined && jsep !== null) {
         Janus.debug("Handling SDP as well...");
         Janus.debug(jsep);
+        if ((navigator.userAgent.toLowerCase().indexOf('firefox') > -1) && (jsep["sdp"].includes("420029"))) { //because firefox devs are stubborn
+          jsep["sdp"] = jsep["sdp"].replace("420029", "42e01f");
+        }
         // Offer from the plugin, let's answer
         streaming[id].createAnswer({
           jsep: jsep,
diff --git a/web/skins/classic/views/js/cycle.js b/web/skins/classic/views/js/cycle.js
index 9e128d0ab..7e7bd0147 100644
--- a/web/skins/classic/views/js/cycle.js
+++ b/web/skins/classic/views/js/cycle.js
@@ -91,6 +91,9 @@ function initCycle() {
               if (jsep !== undefined && jsep !== null) {
                 Janus.debug("Handling SDP as well...");
                 Janus.debug(jsep);
+                if ((navigator.userAgent.toLowerCase().indexOf('firefox') > -1) && (jsep["sdp"].includes("420029"))) { //because firefox devs are stubborn
+                  jsep["sdp"] = jsep["sdp"].replace("420029", "42e01f");
+                }
                 // Offer from the plugin, let's answer
                 streaming2.createAnswer({
                   jsep: jsep,