diff --git a/rules-tests/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector/Fixture/skip_mocks.php.inc b/rules-tests/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector/Fixture/skip_mocks.php.inc
new file mode 100644
index 00000000000..7832cdff7a3
--- /dev/null
+++ b/rules-tests/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector/Fixture/skip_mocks.php.inc
@@ -0,0 +1,16 @@
+<?php
+
+namespace Rector\Tests\Unambiguous\Rector\Expression\FluentSettersToStandaloneCallMethodRector\Fixture;
+
+use PHPUnit\Framework\TestCase;
+use Rector\Tests\Unambiguous\Rector\Expression\FluentSettersToStandaloneCallMethodRector\Source\SomeSetterClass;
+
+final class SkipMocks extends TestCase
+{
+    public function test()
+    {
+        $this->createMock(SomeSetterClass::class)
+            ->expects($this->once())
+            ->method('some');
+    }
+}
diff --git a/rules-tests/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector/Source/SomeSetterClass.php b/rules-tests/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector/Source/SomeSetterClass.php
index 7b0ff3a3afa..36abfd51b98 100644
--- a/rules-tests/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector/Source/SomeSetterClass.php
+++ b/rules-tests/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector/Source/SomeSetterClass.php
@@ -2,7 +2,7 @@
 
 namespace Rector\Tests\Unambiguous\Rector\Expression\FluentSettersToStandaloneCallMethodRector\Source;
 
-final class SomeSetterClass
+class SomeSetterClass
 {
     private ?string $name = null;
 
diff --git a/rules/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector.php b/rules/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector.php
index cd53d7ccce9..8c8907e11f9 100644
--- a/rules/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector.php
+++ b/rules/Unambiguous/Rector/Expression/FluentSettersToStandaloneCallMethodRector.php
@@ -4,6 +4,7 @@
 
 namespace Rector\Unambiguous\Rector\Expression;
 
+use PHPStan\Type\ObjectType;
 use PhpParser\Node;
 use PhpParser\Node\Expr;
 use PhpParser\Node\Expr\Assign;
@@ -13,6 +14,7 @@
 use PhpParser\Node\Name;
 use PhpParser\Node\Stmt\Expression;
 use PhpParser\Node\Stmt\Return_;
+use PHPStan\Reflection\ClassReflection;
 use Rector\Naming\Naming\PropertyNaming;
 use Rector\NodeTypeResolver\Node\AttributeKey;
 use Rector\Rector\AbstractRector;
@@ -107,6 +109,10 @@ public function refactor(Node $node): ?array
 
         $rootExpr = $currentMethodCall;
 
+        if ($this->shouldSkipForVendorOrInternal($firstMethodCall)) {
+            return null;
+        }
+
         $variableName = $this->resolveVariableName($rootExpr);
         $someVariable = new Variable($variableName);
 
@@ -137,4 +143,22 @@ private function resolveVariableName(Expr $expr): string
 
         return 'someVariable';
     }
+
+    private function shouldSkipForVendorOrInternal(MethodCall $firstMethodCall): bool
+    {
+        $callerType = $this->getType($firstMethodCall);
+        if ($callerType instanceof ObjectType) {
+            $classReflection = $callerType->getClassReflection();
+            if (! $classReflection instanceof ClassReflection) {
+                return false;
+            }
+
+            $fileName = $classReflection->getFileName();
+            if ($fileName === null || str_contains($fileName, 'vendor')) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }