diff --git a/classes/CheckFilenames.php b/classes/CheckFilenames.php
index 9d2ecec..6f8f7d4 100644
--- a/classes/CheckFilenames.php
+++ b/classes/CheckFilenames.php
@@ -120,7 +120,7 @@ protected static function replaceUnderscores( $strFile ) {
         $newFilename = str_replace( "__", "_", $strFile );
 
         if( $newFilename != $strFile ) {
-            $newFilename = $this->replaceUnderscores( $newFilename );
+            $newFilename = self::replaceUnderscores( $newFilename );
         }
 
         return $newFilename;