diff --git a/usr.sbin/newsyslog/ptimes.c b/usr.sbin/newsyslog/ptimes.c
--- a/usr.sbin/newsyslog/ptimes.c
+++ b/usr.sbin/newsyslog/ptimes.c
@@ -279,6 +279,10 @@
 				if (tm.tm_mday > daysmon) {
 					tm.tm_mon++;
 					tm.tm_mday = tm.tm_mday - daysmon;
+					if (tm.tm_mon >= 12) {
+						tm.tm_mon = 0;
+						tm.tm_year++;
+					}
 				}
 			}
 			break;