diff --git a/src/Models/Behaviors/HasSlug.php b/src/Models/Behaviors/HasSlug.php
index b05fc8cf3..7824017b2 100644
--- a/src/Models/Behaviors/HasSlug.php
+++ b/src/Models/Behaviors/HasSlug.php
@@ -131,7 +131,7 @@ public function handleSlugsOnSave(): void
 
         foreach ($slugParams as $params) {
             if (in_array($params['locale'], config('twill.slug_utf8_languages', []))) {
-                $params['slug'] = $this->getUtf8Slug($params['slug']);
+                $params['slug'] = $this->getUtf8Slug($params['slug'], ['from_encoding' => mb_list_encodings()]);
             } else {
                 $params['slug'] = Str::slug($params['slug']);
             }
@@ -148,7 +148,7 @@ public function handleSlugsOnSave(): void
     public function updateOrNewSlug(array $slugParams): void
     {
         if (in_array($slugParams['locale'], config('twill.slug_utf8_languages', []))) {
-            $slugParams['slug'] = $this->getUtf8Slug($slugParams['slug']);
+            $slugParams['slug'] = $this->getUtf8Slug($slugParams['slug'], ['from_encoding' => mb_list_encodings()]);
         } else {
             $slugParams['slug'] = Str::slug($slugParams['slug']);
         }
@@ -451,11 +451,15 @@ public function getUtf8Slug(string $str, array $options = []): string
             'lowercase' => true,
             'replacements' => [],
             'transliterate' => true,
+            'from_encoding' => null,
         ];
 
         // Merge options
         $options = array_merge($defaults, $options);
 
+        // Make sure string is in UTF-8 and strip invalid UTF-8 characters
+        $str = mb_convert_encoding((string)$str, 'UTF-8', $options['from_encoding']);
+
         $char_map = [
             // Latin
             'À' => 'A',