diff --git a/src/PhantomInstaller/Installer.php b/src/PhantomInstaller/Installer.php
index f3e4987..3ca5026 100644
--- a/src/PhantomInstaller/Installer.php
+++ b/src/PhantomInstaller/Installer.php
@@ -275,7 +275,7 @@ public static function copyPhantomJsBinaryToBinFolder($targetDir, $binDir)
 
         if ($os !== 'unknown') {
             copy($targetDir . $sourceName, $targetName);
-            chmod($targetName, self::PHANTOMJS_CHMODE);
+            chmod($targetName, static::PHANTOMJS_CHMODE);
         }
 
         self::dropClassWithPathToInstalledBinary($targetName);