diff --git a/TimeSeries.pm b/TimeSeries.pm
index 8818f58..39edd64 100644
--- a/TimeSeries.pm
+++ b/TimeSeries.pm
@@ -31,8 +31,9 @@ use Time::Local;
 use Data::Dumper;
 use HTTP::Date qw(parse_date);
 use Time::Local qw(timegm_nocheck);
+use POSIX qw(strftime);
 
-our $VERSION = do { my @r=(q$Revision: 1.16 $=~/\d+/g);sprintf "%d."."%02d"x$#r,@r};
+our $VERSION = do { my @r=(q$Revision: 1.17 $=~/\d+/g);sprintf "%d."."%02d"x$#r,@r};
 
 =head2 new(%opts)
 
@@ -442,6 +443,9 @@ sub get_ticks {
 
     my @ticks = ();
 
+    my $label;
+    my $nexttime;
+
     if ($lasttime - $firsttime > 3 * 365 * 24 * 3600) {
 	# more than 3 years: 4 ticks/year
 
@@ -450,16 +454,10 @@ sub get_ticks {
 	$mday = 1;
 	$mon = int($mon/3) * 3;
 	$firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	my $time;
-	for (;;) {
-	    $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	    push @ticks, [$time, sprintf('%04d-%02d-%02d', $year+1900, $mon+1, $mday)];
-	    $mon += 3;
-	    if ($mon >= 12) {
-		$mon -= 12; $year++;
-	    }
-	    if ($time > $lasttime) {last}
-	}
+
+	$label = '%Y-%m-%d';
+
+	$nexttime = sub { return add_months($_[0], 3) };
     } elsif ($lasttime - $firsttime > 3 * 30 * 24 * 3600) {
 	# 3 to 36 months: 1 tick/month
 
@@ -467,15 +465,10 @@ sub get_ticks {
 	$sec = $min = $hour = 0;
 	$mday = 1;
 	$firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	my $time;
-	for (;;) {
-	    $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	    push @ticks, [$time, sprintf('%04d-%02d-%02d', $year+1900, $mon+1, $mday)];
-	    if (++$mon >= 12) {
-		$mon = 0; $year++;
-	    }
-	    if ($time > $lasttime) {last}
-	}
+
+	$label = '%Y-%m-%d';
+
+	$nexttime = sub { return add_months($_[0], 1) };
     } elsif ($lasttime - $firsttime > 30 * 24 * 3600) {
 	# 30 ... 90 days: 1 tick/week.
 
@@ -484,56 +477,42 @@ sub get_ticks {
 
 	($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime($firsttime);
 	$sec = $min = $hour = 0;
-	my $time = $firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	for (;;) {
-	    ($sec,$min,$hour,$mday,$mon,$year) = localtime($time);
-	    push @ticks, [$time, sprintf('%04d-%02d-%02d', $year+1900, $mon+1, $mday)];
-	    if ($time > $lasttime) {last}
+	$firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
 
-	    $time += 7 * 24 * 3600;
-	    $time = dstcorr($time);
-	}
+	$label = '%Y-%m-%d';
+
+	$nexttime = sub { return dstcorr($_[0] + 7 * 24 * 3600) };
     } elsif ($lasttime - $firsttime > 8 * 24 * 3600) {
 	# 8 .. 30 days: 1 tick per day.
 
 	my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime($firsttime);
 	$sec = $min = $hour = 0;
-	my $time = $firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	for (;;) {
-	    ($sec,$min,$hour,$mday,$mon,$year) = localtime($time);
-	    push @ticks, [$time, sprintf('%04d-%02d-%02d', $year+1900, $mon+1, $mday)];
-	    if ($time > $lasttime) {last}
+	$firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
 
-	    $time += 24 * 3600;
-	    $time = dstcorr($time);
-	}
+	$label = '%Y-%m-%d';
+
+	$nexttime = sub { return dstcorr($_[0] + 24 * 3600) };
     } elsif ($lasttime - $firsttime > 2 * 24 * 3600) {
 	# 2 .. 8 days: 1 tick/4 hours
 
 	my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime($firsttime);
-	$sec = $min = $hour = 0;
-	my $time = $firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	for (;;) {
-	    ($sec,$min,$hour,$mday,$mon,$year) = localtime($time);
-	    push @ticks, [$time, sprintf('%04d-%02d-%02d %02d:%02d', $year+1900, $mon+1, $mday, $hour, $min)];
-	    if ($time > $lasttime) {last}
+	$sec = $min = 0;
+	$hour = int($hour / 4) * 4;
+	$firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
 
-	    $time += 4 * 3600;
-	    $time = dstcorr($time, 4 * 3600);
-	}
+	$label = '%Y-%m-%d %H:%M';
+
+	$nexttime = sub { return dstcorr($_[0] + 4 * 3600, 4 * 3600) };
     } elsif ($lasttime - $firsttime > 6 * 3600) {
 	# 6 hours to 2 days: 1 tick per hour.
 
 	my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime($firsttime);
 	$sec = $min = 0;
-	my $time = $firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	for (;;) {
-	    ($sec,$min,$hour,$mday,$mon,$year) = localtime($time);
-	    push @ticks, [$time, sprintf('%04d-%02d-%02d %02d:%02d', $year+1900, $mon+1, $mday, $hour, $min)];
-	    if ($time > $lasttime) {last}
+	$firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
 
-	    $time += 3600;
-	}
+	$label = '%Y-%m-%d %H:%M';
+
+	$nexttime = sub { return $_[0] + 3600 };
     } else {
 	# less than 6 hours: 1 tick per minute.
 	# (ok, that's too much - need to find some intermediate steps,
@@ -542,15 +521,31 @@ sub get_ticks {
 	my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime($firsttime);
 	$sec = 0;
 	my $time = $firsttime = timelocal($sec,$min,$hour,$mday,$mon,$year);
-	for (;;) {
-	    ($sec,$min,$hour,$mday,$mon,$year) = localtime($time);
-	    push @ticks, [$time, sprintf('%04d-%02d-%02d %02d:%02d', $year+1900, $mon+1, $mday, $hour, $min)];
-	    if ($time > $lasttime) {last}
 
-	    $time += 60;
-	}
+	$label = '%Y-%m-%d %H:%M';
+
+	$nexttime = sub { return $_[0] + 60 };
     }
+
+    my $time = $firsttime;
+    for (;;) {
+	push @ticks, [$time, strftime($label, localtime($time))];
+	if ($time > $lasttime) {last}
+	$time = $nexttime->($time);
+    }
+
     return @ticks;
 }
 
+sub add_months {
+    my ($time, $d_mon) = @_;
+    my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)
+	= localtime($time);
+    $mon += $d_mon;
+    if ($mon >= 12) {
+	$mon -= 12; $year++;
+    }
+    $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
+};
+
 1;