diff --git a/src/Twig/Component/Badge.php b/src/Twig/Component/Badge.php
index 840f06a..715d9f1 100644
--- a/src/Twig/Component/Badge.php
+++ b/src/Twig/Component/Badge.php
@@ -20,13 +20,13 @@ final class Badge
 
     /**
      * @param ?BadgeableInterface $obj The object to be converted into a badge.
-     * @param string $class            Extra classes to add to the badge element.
+     * @param ?string $class           Extra classes to add to the badge element.
      *                                 These will override the base classes in case
      *                                 of conflicts.
      * @param ?string $colour          Specify the colour of an objectless badge.
      * @param bool $outline            If the badge should be rendered as an outline.
      */
-    public function mount(?BadgeableInterface $obj = null, string $class = '', string $colour = null, bool $outline = false): void
+    public function mount(?BadgeableInterface $obj = null, ?string $class = null, string $colour = null, bool $outline = false): void
     {
         if (!$obj && !$colour) {
             throw new \RuntimeException(sprintf("You must specify either a colour an instance of \"%s\".", BadgeableInterface::class));
@@ -60,7 +60,7 @@ final class Badge
             $classes = sprintf('text-white %s %s %s %s', $palette->borderColourClass, $palette->backgroundColourClass, $this->baseClasses, $class);
         }
 
-        $this->finalClasses = $merger->merge($classes);
+        $this->finalClasses = $merger->merge(trim($classes));
     }
 }