diff --git a/src/Parser.php b/src/Parser.php
index 5cd8c34..c21e2b6 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -160,10 +160,11 @@ private function parseInput(string $name): Name
         if (count($segments) > 1) {
             // Reuse the split while preserving subclass parseSplitName() overrides.
             $tail = array_slice($segments, 1);
-            $this->preSplitTailStack[] = [implode(',', $tail), $tail];
+            $given = implode(',', $tail);
+            $this->preSplitTailStack[] = [$given, $tail];
 
             try {
-                return $this->parseSplitName($segments[0], implode(',', $tail))
+                return $this->parseSplitName($segments[0], $given)
                     ->setSource($name, $this->tokenizeSegments($segments));
             } finally {
                 array_pop($this->preSplitTailStack);
diff --git a/tests/ParserTest.php b/tests/ParserTest.php
index 7f5ca81..5da690c 100644
--- a/tests/ParserTest.php
+++ b/tests/ParserTest.php
@@ -815,6 +815,26 @@ protected function parseSplitName(string $surname, string $given): Name
         $this->assertSame('MD', $name->getSuffix());
     }
 
+    public function testSplitHookCanRewriteSharedGivenString(): void
+    {
+        $parser = new class extends Parser {
+            #[\Override]
+            protected function parseSplitName(string $surname, string $given): Name
+            {
+                $given[1] = 'K';
+
+                return parent::parseSplitName($surname, $given);
+            }
+        };
+
+        $name = $parser->parse('Smith, Jane, MD');
+
+        $this->assertSame('Kane', $name->getFirstname());
+        $this->assertSame('Smith', $name->getLastname());
+        $this->assertSame('MD', $name->getSuffix());
+        $this->assertSame('Smith, Jane, MD', $name->getSource());
+    }
+
     public function testSubclassMayOverrideSettersWithConcreteReturnType(): void
     {
         // The released 1.x API permits concrete Parser returns in subclass setters.