--- a/xpcom/threads/nsThreadUtils.cpp
+++ b/xpcom/threads/nsThreadUtils.cpp
@@ -35,19 +35,26 @@ NS_IMPL_ISUPPORTS(IdlePeriod, nsIIdlePer
 
 NS_IMETHODIMP
 IdlePeriod::GetIdlePeriodHint(TimeStamp* aIdleDeadline)
 {
   *aIdleDeadline = TimeStamp();
   return NS_OK;
 }
 
+// NS_IMPL_NAMED_* relies on the mName field, which is not present on
+// release or beta. Instead, fall back to using "Runnable" for all
+// runnables.
+#ifdef RELEASE_OR_BETA
+NS_IMPL_ISUPPORTS(Runnable, nsIRunnable, nsINamed)
+#else
 NS_IMPL_NAMED_ADDREF(Runnable, mName)
 NS_IMPL_NAMED_RELEASE(Runnable, mName)
 NS_IMPL_QUERY_INTERFACE(Runnable, nsIRunnable, nsINamed)
+#endif
 
 NS_IMETHODIMP
 Runnable::Run()
 {
   // Do nothing
   return NS_OK;
 }