diff -Naur a/src/utils.c b/src/utils.c
--- a/src/utils.c	2019-06-16 20:04:39.000000000 +0100
+++ b/src/utils.c	2019-08-01 16:12:00.864953675 +0100
@@ -526,9 +526,11 @@
 	t.tm_mon += delta_month;
 	t.tm_mday += delta_day;
 
+  t.tm_isdst = -1;
 	if (mktime(&t) == -1) {
 		return 1;
 	} else {
+		t.tm_isdst = -1;
 		*date = t;
 		return 0;
 	}