1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index e3fe83a23cf7..29cf1457ca10 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -120,7 +120,8 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
         t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
 
         if (cmos->day_alrm) {
-                t->time.tm_mday = CMOS_READ(cmos->day_alrm);
+                /* ignore upper bits on readback per ACPI spec */
+                t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
                 if (!t->time.tm_mday)
                         t->time.tm_mday = -1;