diff --git a/src/Symfony/Component/String/AbstractUnicodeString.php b/src/Symfony/Component/String/AbstractUnicodeString.php
index 239f234239fb8..0f840f19d717d 100644
--- a/src/Symfony/Component/String/AbstractUnicodeString.php
+++ b/src/Symfony/Component/String/AbstractUnicodeString.php
@@ -366,8 +366,8 @@ public function reverse(): parent
 
     public function snake(): parent
     {
-        $str = $this->camel();
-        $str->string = mb_strtolower(preg_replace(['/(\p{Lu}+)(\p{Lu}\p{Ll})/u', '/([\p{Ll}0-9])(\p{Lu})/u'], '\1_\2', $str->string), 'UTF-8');
+        $str = clone $this;
+        $str->string = str_replace(' ', '_', mb_strtolower(preg_replace(['/(\p{Lu}+)(\p{Lu}\p{Ll})/u', '/([\p{Ll}0-9])(\p{Lu})/u'], '\1 \2', $str->string), 'UTF-8'));
 
         return $str;
     }
diff --git a/src/Symfony/Component/String/ByteString.php b/src/Symfony/Component/String/ByteString.php
index 05170da801c0e..86887d7901a74 100644
--- a/src/Symfony/Component/String/ByteString.php
+++ b/src/Symfony/Component/String/ByteString.php
@@ -366,8 +366,8 @@ public function slice(int $start = 0, ?int $length = null): parent
 
     public function snake(): parent
     {
-        $str = $this->camel();
-        $str->string = strtolower(preg_replace(['/([A-Z]+)([A-Z][a-z])/', '/([a-z\d])([A-Z])/'], '\1_\2', $str->string));
+        $str = clone $this;
+        $str->string = str_replace(' ', '_', strtolower(preg_replace(['/([A-Z]+)([A-Z][a-z])/', '/([a-z\d])([A-Z])/'], '\1 \2', $str->string)));
 
         return $str;
     }
diff --git a/src/Symfony/Component/String/Tests/AbstractAsciiTestCase.php b/src/Symfony/Component/String/Tests/AbstractAsciiTestCase.php
index 8bde9bc8b3df3..132d558dbade4 100644
--- a/src/Symfony/Component/String/Tests/AbstractAsciiTestCase.php
+++ b/src/Symfony/Component/String/Tests/AbstractAsciiTestCase.php
@@ -1077,6 +1077,8 @@ public static function provideSnake()
             ['symfony_is_great', 'symfonyIsGREAT'],
             ['symfony_is_really_great', 'symfonyIsREALLYGreat'],
             ['symfony', 'SYMFONY'],
+            ['symfony_is_great', 'SYMFONY IS GREAT'],
+            ['symfony_is_great', 'SYMFONY_IS_GREAT'],
         ];
     }