diff --git a/usr.sbin/newsyslog/newsyslog.c b/usr.sbin/newsyslog/newsyslog.c
--- a/usr.sbin/newsyslog/newsyslog.c
+++ b/usr.sbin/newsyslog/newsyslog.c
@@ -2615,7 +2615,7 @@
 		mtime = sb.st_mtime;
 	}
 
-	return ((int)(ptimeget_secs(timenow) - mtime + 1800) / 3600);
+	return ((int)(ptimeget_secs(timenow) - mtime + 180) / 3600);
 }
 
 /* Skip Over Blanks */
diff --git a/usr.sbin/newsyslog/tests/legacy_test.sh b/usr.sbin/newsyslog/tests/legacy_test.sh
--- a/usr.sbin/newsyslog/tests/legacy_test.sh
+++ b/usr.sbin/newsyslog/tests/legacy_test.sh
@@ -417,6 +417,51 @@
 	tmpdir_clean
 }
 
+tests_interval_rotate() {
+	local hours ext h
+
+	hours="$1"
+	ext="$2"
+
+	tmpdir_create
+
+	begin "create file" -newdir
+	run_newsyslog -C
+	ckfe ${LOGFNAME}
+	end
+
+	# old file doesn't exist - forced rotation
+	begin "rotate interval 0"
+	run_newsyslog
+	ckfe ${LOGFNAME}
+	chkfcnt 1 ${dir}${LOGFNAME}.*
+	end
+
+	# emulate newsyslog runs every 5 minutes
+	begin "rotate interval less than ${hours} hours"
+	m=0
+	while [ $(expr ${m} / 60 ) -lt ${hours} ]; do
+		touch -t $(date -v -${m}M +%Y%m%d%H%M) ${LOGFNAME}.0
+		run_newsyslog
+		ckfe ${LOGFNAME}
+		chkfcnt 1 ${dir}${LOGFNAME}.*
+		if [ $OK != 1 ]; then
+			break;
+		fi
+		m=$(expr ${m} + 5)
+	done
+	end
+
+	begin "rotate interval ${hours} hours"
+	touch -t $(date -v -${hours}H +%Y%m%d%H%M) ${LOGFNAME}.0
+	run_newsyslog
+	ckfe ${LOGFNAME}
+	chkfcnt 2 ${dir}${LOGFNAME}.*
+	end
+
+	tmpdir_clean
+}
+
 tests_rfc5424() {
 	local dir ext name_postfix newsyslog_args
 
@@ -526,7 +571,7 @@
 	tmpdir_clean
 }
 
-echo 1..185
+echo 1..193
 mkdir -p ${TMPDIR}
 cd ${TMPDIR}
 
@@ -638,4 +683,10 @@
 echo "$LOGFPATH 640  3     *    @T00  NCZ" > newsyslog.conf
 tests_normal_rotate_recompress
 
+# Interval based rotation
+echo "$LOGFPATH	640  3	   *	1  NC" > newsyslog.conf
+tests_interval_rotate 1
+echo "$LOGFPATH	640  3	   *	2  NC" > newsyslog.conf
+tests_interval_rotate 2
+
 rm -rf "${TMPDIR}"