--- a/netwerk/dns/nsHostResolver.cpp
+++ b/netwerk/dns/nsHostResolver.cpp
@@ -1857,16 +1857,20 @@ nsHostResolver::ThreadFunc()
         if (LOOKUP_RESOLVEAGAIN == CompleteLookup(rec, status, ai, rec->pb)) {
             // leave 'rec' assigned and loop to make a renewed host resolve
             LOG(("DNS lookup thread - Re-resolving host [%s].\n", rec->host.get()));
         } else {
             rec = nullptr;
         }
     } while(true);
 
+    nsCOMPtr<nsIThread> thread = NS_GetCurrentThread();
+    NS_DispatchToMainThread(NS_NewRunnableFunction("nsHostResolver::ThreadFunc::AsyncShutdown", [thread]() {
+        thread->AsyncShutdown();
+    }));
     mThreadCount--;
     LOG(("DNS lookup thread - queue empty, thread finished.\n"));
 }
 
 void
 nsHostResolver::SetCacheLimits(uint32_t aMaxCacheEntries,
                                uint32_t aDefaultCacheEntryLifetime,
                                uint32_t aDefaultGracePeriod)