--- a/netwerk/test/unit/test_be_conservative.js
+++ b/netwerk/test/unit/test_be_conservative.js
@@ -76,28 +76,37 @@ class InputStreamCallback {
   }
 }
 
 class TLSServerSecurityObserver {
   constructor(input, output) {
     this.input = input;
     this.output = output;
     this.callbacks = [];
+    this.stopped = false;
   }
 
   onHandshakeDone(socket, status) {
     do_print("TLS handshake done");
     do_print(`TLS version used: ${status.tlsVersionUsed}`);
 
+    if (this.stopped) {
+      do_print("handshake done callback stopped - closing streams and bailing");
+      this.input.close();
+      this.output.close();
+      return;
+    }
+
     let callback = new InputStreamCallback(this.output);
     this.callbacks.push(callback);
     this.input.asyncWait(callback, 0, 0, Services.tm.currentThread);
   }
 
   stop() {
+    this.stopped = true;
     this.callbacks.forEach((callback) => {
       callback.stop();
     });
   }
 }
 
 class ServerSocketListener {
   constructor() {