diff --git a/vl.c b/vl.c
index 624da0fd3c..641629b1ce 100644
--- a/vl.c
+++ b/vl.c
@@ -460,8 +460,11 @@ int qemu_timedate_diff(struct tm *tm)
     if (rtc_date_offset == -1)
         if (rtc_utc)
             seconds = mktimegm(tm);
-        else
-            seconds = mktime(tm);
+        else {
+            struct tm tmp = *tm;
+            tmp.tm_isdst = -1; /* use timezone to figure it out */
+            seconds = mktime(&tmp);
+	}
     else
         seconds = mktimegm(tm) + rtc_date_offset;