diff --git a/src/Sanitizers/Capitalize.php b/src/Sanitizers/Capitalize.php
index 31094ca..3b28e94 100644
--- a/src/Sanitizers/Capitalize.php
+++ b/src/Sanitizers/Capitalize.php
@@ -3,6 +3,7 @@
 namespace ArondeParon\RequestSanitizer\Sanitizers;
 
 use ArondeParon\RequestSanitizer\Contracts\Sanitizer;
+use Illuminate\Support\Str;
 
 class Capitalize implements Sanitizer
 {
@@ -12,6 +13,6 @@ class Capitalize implements Sanitizer
      */
     public function sanitize($input)
     {
-        return ucfirst($input);
+        return Str::ucfirst($input);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Sanitizers/Lowercase.php b/src/Sanitizers/Lowercase.php
index 58a7bfe..6cdd5fb 100644
--- a/src/Sanitizers/Lowercase.php
+++ b/src/Sanitizers/Lowercase.php
@@ -3,6 +3,7 @@
 namespace ArondeParon\RequestSanitizer\Sanitizers;
 
 use ArondeParon\RequestSanitizer\Contracts\Sanitizer;
+use Illuminate\Support\Str;
 
 class Lowercase implements Sanitizer
 {
@@ -12,6 +13,6 @@ class Lowercase implements Sanitizer
      */
     public function sanitize($input)
     {
-        return strtolower($input);
+        return Str::lower($input);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Sanitizers/Uppercase.php b/src/Sanitizers/Uppercase.php
index e5ac2c7..07e47f5 100644
--- a/src/Sanitizers/Uppercase.php
+++ b/src/Sanitizers/Uppercase.php
@@ -3,6 +3,7 @@
 namespace ArondeParon\RequestSanitizer\Sanitizers;
 
 use ArondeParon\RequestSanitizer\Contracts\Sanitizer;
+use Illuminate\Support\Str;
 
 class Uppercase implements Sanitizer
 {
@@ -12,6 +13,6 @@ class Uppercase implements Sanitizer
      */
     public function sanitize($input)
     {
-        return strtoupper($input);
+        return Str::upper($input);
     }
-}
\ No newline at end of file
+}