diff --git a/devtools/server/tracer/tracer.jsm b/devtools/server/tracer/tracer.jsm
index d5ac88d6496a..8fdbc2c0b57e 100644
--- a/devtools/server/tracer/tracer.jsm
+++ b/devtools/server/tracer/tracer.jsm
@@ -327,7 +327,10 @@ function stopTracing() {
 function addTracingListener(listener) {
   listeners.add(listener);
 
-  if (activeTracer?.isTracing()) {
+  if (
+    activeTracer?.isTracing() &&
+    typeof listener.onTracingToggled == "function"
+  ) {
     listener.onTracingToggled(true);
   }
 }