diff --git a/html/includes/graphs/generic_multi_line.inc.php b/html/includes/graphs/generic_multi_line.inc.php
index d80c2b4d7..5d4b18548 100644
--- a/html/includes/graphs/generic_multi_line.inc.php
+++ b/html/includes/graphs/generic_multi_line.inc.php
@@ -42,7 +42,7 @@ foreach ($rrd_list as $rrd) {
     }
 
     if (!empty($rrd['area']) && empty($rrd['areacolour'])) {
-        $rrd['areacolour'] = $colour . "20";
+        $rrd['areacolour'] = substr($colour, 0, 6) . "20";
     }
 
     $ds = $rrd['ds'];