diff --git a/toolkit/modules/AsyncShutdown.jsm b/toolkit/modules/AsyncShutdown.jsm
index b6420e2d71d1..372dbcb2fb08 100644
--- a/toolkit/modules/AsyncShutdown.jsm
+++ b/toolkit/modules/AsyncShutdown.jsm
@@ -453,7 +453,7 @@ function Barrier(name) {
         frames.push(frame.filename + ":" + frame.name + ":" + frame.lineNumber);
         frame = frame.caller;
       }
-      let stack = Task.Debugging.generateReadableStack(frames.join("\n"));
+      let stack = Task.Debugging.generateReadableStack(frames.join("\n")).split("\n");
 
       let set = this._conditions.get(condition);
       if (!set) {
diff --git a/toolkit/modules/tests/xpcshell/test_AsyncShutdown.js b/toolkit/modules/tests/xpcshell/test_AsyncShutdown.js
index 273c43e18541..90d50a46e879 100644
--- a/toolkit/modules/tests/xpcshell/test_AsyncShutdown.js
+++ b/toolkit/modules/tests/xpcshell/test_AsyncShutdown.js
@@ -293,8 +293,8 @@ add_task(function* test_state() {
   Assert.equal(state.filename, filename);
   Assert.equal(state.lineNumber, lineNumber + 1);
   Assert.equal(state.name, BLOCKER_NAME);
-  Assert.ok(state.stack.contains("test_state"), "The stack contains the caller function's name");
-  Assert.ok(state.stack.contains(filename), "The stack contains the calling file's name");
+  Assert.ok(state.stack.some(x => x.contains("test_state")), "The stack contains the caller function's name");
+  Assert.ok(state.stack.some(x => x.contains(filename)), "The stack contains the calling file's name");
 
   deferred.resolve();
   yield promiseDone;