diff --git a/html/includes/graphs/generic_multi_simplex_seperated.inc.php b/html/includes/graphs/generic_multi_simplex_seperated.inc.php
index c86192a5ed..0ce6c69101 100644
--- a/html/includes/graphs/generic_multi_simplex_seperated.inc.php
+++ b/html/includes/graphs/generic_multi_simplex_seperated.inc.php
@@ -24,8 +24,14 @@ foreach ($rrd_list as $i => $rrd)
   }
 
   $rrd_options .= " DEF:".$rrd['ds'].$i."=".$rrd['filename'].":".$rrd['ds'].":AVERAGE ";
-  $rrd_options .= " DEF:".$rrd['ds'].$i."min=".$rrd['filename'].":".$rrd['ds'].":MIN ";
-  $rrd_options .= " DEF:".$rrd['ds'].$i."max=".$rrd['filename'].":".$rrd['ds'].":MAX ";
+  if($simple_rrd) 
+  {
+    $rrd_options .= " CDEF:".$rrd['ds'].$i."min=".$rrd['ds'].$i." ";
+    $rrd_options .= " CDEF:".$rrd['ds'].$i."max=".$rrd['ds'].$i." ";
+  } else {
+    $rrd_options .= " DEF:".$rrd['ds'].$i."min=".$rrd['filename'].":".$rrd['ds'].":MIN ";
+    $rrd_options .= " DEF:".$rrd['ds'].$i."max=".$rrd['filename'].":".$rrd['ds'].":MAX ";
+  }
 
   ## Suppress totalling?
   if (!$nototal)