diff --git a/src/CSS.php b/src/CSS.php
index cdc33b0..99eb22d 100644
--- a/src/CSS.php
+++ b/src/CSS.php
@@ -258,7 +258,7 @@ protected function importFiles($source, $content)
      * @param  string[optional] $path Path to write the data to.
      * @return string           The minified data.
      */
-    protected function execute($path = null)
+    public function execute($path = null)
     {
         $content = '';
 
diff --git a/src/Minify.php b/src/Minify.php
index 10c6a30..7d2140b 100644
--- a/src/Minify.php
+++ b/src/Minify.php
@@ -178,7 +178,7 @@ public function cache(CacheItemInterface $item)
      * @param  string[optional] $path Path to write the data to.
      * @return string           The minified data.
      */
-    abstract protected function execute($path = null);
+    abstract public function execute($path = null);
 
     /**
      * Register a pattern to execute against the source content.