diff --git a/hw/arm/omap1.c b/hw/arm/omap1.c
index b433748c607d..b28e0521b46b 100644
--- a/hw/arm/omap1.c
+++ b/hw/arm/omap1.c
@@ -2709,8 +2709,8 @@ static void omap_rtc_write(void *opaque, hwaddr addr,
             s->ti += ti[1];
         } else {
             /* A less accurate version */
-            s->ti -= (s->current_tm.tm_year % 100) * 31536000;
-            s->ti += from_bcd(value) * 31536000;
+            s->ti -= (time_t)(s->current_tm.tm_year % 100) * 31536000;
+            s->ti += (time_t)from_bcd(value) * 31536000;
         }
         return;