diff --git a/system/libraries/Benchmark.php b/system/libraries/Benchmark.php
index d29e917..c20a542 100644
--- a/system/libraries/Benchmark.php
+++ b/system/libraries/Benchmark.php
@@ -71,9 +71,16 @@
     	{
 			return '{elapsed_time}';
     	}
+    	
+    	if ( ! isset($this->marker[$point1]))
+    	{
+    		return '';
+    	}
     	    
     	if ( ! isset($this->marker[$point2]))
+    	{
         	$this->marker[$point2] = microtime();
+        }
         	    
         list($sm, $ss) = explode(' ', $this->marker[$point1]);
         list($em, $es) = explode(' ', $this->marker[$point2]);