diff --git a/icons/icon.pl b/icons/icon.pl
index b9cce7e..d0c5a8e 100755
--- a/icons/icon.pl
+++ b/icons/icon.pl
@@ -203,7 +203,8 @@ sub readicon {
 		$currbits += $depth;
 		if ($x < $w && defined ($pix = $data->[$y*$w+$x])) {
 		    if (!defined $pal{$pix}) {
-			die "illegal colour value $pix at pixel $i in $filename\n";
+                        my $pixprintable = unpack "H*", $pix;
+			die "illegal colour value $pixprintable at pixel ($x,$y) in $filename\n";
 		    }
 		    $currbyte |= $pal{$pix};
 		}