diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 2897af0857e9..968ab19e51c8 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -491,6 +491,13 @@ static inline void timer_set_idx(struct timer_list *timer, unsigned int idx)
  * Helper function to calculate the array index for a given expiry
  * time.
  */
+#ifndef CONFIG_SCHED_WALT
+static inline unsigned calc_index(unsigned expires, unsigned lvl)
+{
+	expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl);
+	return LVL_OFFS(lvl) + (expires & LVL_MASK);
+}
+#else
 static inline unsigned calc_index(unsigned expires, unsigned lvl)
 {
 	if (lvl != 0 && (expires & ~(UINT_MAX << LVL_SHIFT(lvl))))
@@ -500,6 +507,7 @@ static inline unsigned calc_index(unsigned expires, unsigned lvl)
 
 	return LVL_OFFS(lvl) + (expires & LVL_MASK);
 }
+#endif
 
 static int calc_wheel_index(unsigned long expires, unsigned long clk)
 {