diff --git a/xpcom/glue/nsThreadUtils.h b/xpcom/glue/nsThreadUtils.h
index a6321a99ae0..0e2d1798d97 100644
--- a/xpcom/glue/nsThreadUtils.h
+++ b/xpcom/glue/nsThreadUtils.h
@@ -71,9 +71,15 @@ NS_NewNamedThread(const char (&name)[LEN],
                   nsIRunnable *initialEvent = nullptr,
                   uint32_t stackSize = nsIThreadManager::DEFAULT_STACK_SIZE)
 {
-    nsresult rv = NS_NewThread(result, initialEvent, stackSize);
-    NS_SetThreadName<LEN>(*result, name);
-    return rv;
+  nsresult rv = NS_NewThread(result, nullptr, stackSize);
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_SetThreadName<LEN>(*result, name);
+  if (initialEvent) {
+    rv = (*result)->Dispatch(initialEvent, NS_DISPATCH_NORMAL);
+    NS_WARN_IF_FALSE(NS_SUCCEEDED(rv), "Initial event dispatch failed");
+  }
+
+  return rv;
 }
 
 /**