diff --git a/library/Businessprocess/Storage/LegacyStorage.php b/library/Businessprocess/Storage/LegacyStorage.php
index c330cc7..2fd7d45 100644
--- a/library/Businessprocess/Storage/LegacyStorage.php
+++ b/library/Businessprocess/Storage/LegacyStorage.php
@@ -163,7 +163,7 @@ class LegacyStorage extends Storage
         $file = $this->currentFilename = $this->getFilename($name);
         $fh = @fopen($file, 'r');
         if (! $fh) {
-            throw new SystemPermissionException('Could not open ' . $file);
+            throw new SystemPermissionException('Could not open "%s"', $file);
         }
 
         $this->parsing_line_number = 0;