diff --git a/rules-tests/CodeQuality/Rector/MethodCall/AssertEmptyNullableObjectToAssertInstanceofRector/Fixture/keep_custom_message.php.inc b/rules-tests/CodeQuality/Rector/MethodCall/AssertEmptyNullableObjectToAssertInstanceofRector/Fixture/keep_custom_message.php.inc
new file mode 100644
index 00000000..faa74b0a
--- /dev/null
+++ b/rules-tests/CodeQuality/Rector/MethodCall/AssertEmptyNullableObjectToAssertInstanceofRector/Fixture/keep_custom_message.php.inc
@@ -0,0 +1,37 @@
+<?php
+
+namespace Rector\PHPUnit\Tests\CodeQuality\Rector\MethodCall\AssertEmptyNullableObjectToAssertInstanceofRector\Fixture;
+
+use CodeQuality\Rector\MethodCall\AssertEmptyNullableObjectToAssertInstanceofRector\Source\SomeTypeObject;
+use PHPUnit\Framework\TestCase;
+
+final class KeepCustomMessage extends TestCase
+{
+    public function test()
+    {
+        $someObject = mt_rand(0, 1) ? new SomeTypeObject() : null;
+
+        $this->assertNull($someObject, 'some message');
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\PHPUnit\Tests\CodeQuality\Rector\MethodCall\AssertEmptyNullableObjectToAssertInstanceofRector\Fixture;
+
+use CodeQuality\Rector\MethodCall\AssertEmptyNullableObjectToAssertInstanceofRector\Source\SomeTypeObject;
+use PHPUnit\Framework\TestCase;
+
+final class KeepCustomMessage extends TestCase
+{
+    public function test()
+    {
+        $someObject = mt_rand(0, 1) ? new SomeTypeObject() : null;
+
+        $this->assertNotInstanceOf(\CodeQuality\Rector\MethodCall\AssertEmptyNullableObjectToAssertInstanceofRector\Source\SomeTypeObject::class, $someObject, 'some message');
+    }
+}
+
+?>
diff --git a/rules/CodeQuality/Rector/MethodCall/AssertEmptyNullableObjectToAssertInstanceofRector.php b/rules/CodeQuality/Rector/MethodCall/AssertEmptyNullableObjectToAssertInstanceofRector.php
index 1edefd41..de019754 100644
--- a/rules/CodeQuality/Rector/MethodCall/AssertEmptyNullableObjectToAssertInstanceofRector.php
+++ b/rules/CodeQuality/Rector/MethodCall/AssertEmptyNullableObjectToAssertInstanceofRector.php
@@ -47,7 +47,6 @@ public function test()
     }
 }
 CODE_SAMPLE
-
                     ,
                     <<<'CODE_SAMPLE'
 use PHPUnit\Framework\TestCase;
@@ -99,7 +98,6 @@ public function refactor(Node $node): ?Node
         }
 
         $firstArgType = $this->getType($firstArg->value);
-
         if (! $firstArgType instanceof UnionType) {
             return null;
         }
@@ -118,9 +116,15 @@ public function refactor(Node $node): ?Node
 
         $fullyQualified = new FullyQualified($pureType->getClassName());
 
+        $customMessageArg = $node->getArgs()[1] ?? null;
+
         $node->args[0] = new Arg(new ClassConstFetch($fullyQualified, 'class'));
         $node->args[1] = $firstArg;
 
+        if ($customMessageArg instanceof Arg) {
+            $node->args[] = $customMessageArg;
+        }
+
         return $node;
     }
 }