--- a/js/src/vm/SavedStacks.cpp
+++ b/js/src/vm/SavedStacks.cpp
@@ -135,17 +135,17 @@ LiveSavedFrameCache::find(JSContext* cx,
         // since we're going to push new cache entries for all frames younger
         // than frameIter, we must pop it anyway.
         frames->popBack();
 
         // If the frame's bit was set, the frame should always have an entry in
         // the cache. (If we purged the entire cache because its SavedFrames had
         // been captured for a different compartment, then we would have
         // returned early above.)
-        MOZ_ASSERT(!frames->empty());
+        MOZ_ALWAYS_TRUE(!frames->empty());
     }
 
     // The youngest valid frame may have run some code, so its current pc may
     // not match its cache entry's pc. In this case, just treat it as a miss. No
     // older frame has executed any code; it would have been necessary to pop
     // this frame for that to happen, but this frame's bit is set.
     if (pc != frames->back().pc) {
         frames->popBack();