--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -3159,17 +3159,16 @@ EndMarkPhase(JSRuntime *rt)
     }
 
     /*
      * To avoid the black->gray edge, we completely clear the mark bits of all
      * uncollected compartments. This is safe, although it may prevent the
      * cycle collector from collecting some dead objects.
      */
     if (foundBlackGray) {
-        JS_ASSERT(false);
         for (CompartmentsIter c(rt); !c.done(); c.next()) {
             if (!c->isCollecting())
                 c->arenas.unmarkAll();
         }
     }
 
     rt->gcMarker.stop();