diff --git a/scripts/bootgraph.pl b/scripts/bootgraph.pl
index 5e7316e..ea2b079 100644
--- a/scripts/bootgraph.pl
+++ b/scripts/bootgraph.pl
@@ -37,7 +37,10 @@
 # 	dmesg | perl scripts/bootgraph.pl > output.svg
 #
 
-my %start, %end;
+use strict;
+
+my %start;
+my %end;
 my $done = 0;
 my $maxtime = 0;
 my $firsttime = 100;
@@ -105,12 +108,14 @@
 my $stylecounter = 0;
 my %rows;
 my $rowscount = 1;
+my $key;
+my $value;
 while (($key,$value) = each %start) {
 	my $duration = $end{$key} - $start{$key};
 
 	if ($duration >= $threshold) {
-		my $s, $s2, $e, $y;
-		$pid = $pids{$key};
+		my ($s, $s2, $e, $w, $y, $y2, $style);
+		my $pid = $pids{$key};
 
 		if (!defined($rows{$pid})) {
 			$rows{$pid} = $rowscount;
@@ -140,9 +145,9 @@
 my $time = $firsttime;
 my $step = ($maxtime - $firsttime) / 15;
 while ($time < $maxtime) {
-	my $s2 = ($time - $firsttime) * $mult;
+	my $s3 = ($time - $firsttime) * $mult;
 	my $tm = int($time * 100) / 100.0;
-	print "<text transform=\"translate($s2,89) rotate(90)\">$tm</text>\n";
+	print "<text transform=\"translate($s3,89) rotate(90)\">$tm</text>\n";
 	$time = $time + $step;
 }