diff --git a/_tests/ParallelOutput.php b/_tests/ParallelOutput.php
index 7c03df1c..719af164 100644
--- a/_tests/ParallelOutput.php
+++ b/_tests/ParallelOutput.php
@@ -65,7 +65,7 @@ protected function updateProcessStatus( Process $process, $output ) {
 	}
 
 	protected function formatStatusWithTime( $taskId, $status ) {
-		$elapsed = microtime( true ) - $this->startTimes[ $taskId ];
+		$elapsed = max( 0, intval( microtime( true ) - $this->startTimes[ $taskId ] ) );
 		$minutes = floor( $elapsed / 60 );
 		$seconds = str_pad( (int) ceil( $elapsed % 60 ), 2, '0', STR_PAD_LEFT );