diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 940633c63254..4f014be7a4b8 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1268,8 +1268,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
 
 	if (unlikely(ret)) {
 		__set_current_state(TASK_RUNNING);
-		if (rt_mutex_has_waiters(lock))
-			remove_waiter(lock, &waiter);
+		remove_waiter(lock, &waiter);
 		rt_mutex_handle_deadlock(ret, chwalk, &waiter);
 	}
 
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 68686b3ec3c1..d1d62f942be2 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -52,12 +52,13 @@ static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
 static inline struct rt_mutex_waiter *
 rt_mutex_top_waiter(struct rt_mutex *lock)
 {
-	struct rt_mutex_waiter *w;
-
-	w = rb_entry(lock->waiters.rb_leftmost,
-		     struct rt_mutex_waiter, tree_entry);
-	BUG_ON(w->lock != lock);
+	struct rb_node *leftmost = rb_first_cached(&lock->waiters);
+	struct rt_mutex_waiter *w = NULL;
 
+	if (leftmost) {
+		w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
+		BUG_ON(w->lock != lock);
+	}
 	return w;
 }