diff --git a/extension.neon b/extension.neon
index 1fe57183..21e8e248 100644
--- a/extension.neon
+++ b/extension.neon
@@ -21,6 +21,10 @@ services:
 			repositoryClass: %doctrine.repositoryClass%
 		tags:
 			- phpstan.broker.dynamicMethodReturnTypeExtension
+	-
+		class: PHPStan\Type\Doctrine\ObjectManagerMergeDynamicReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension
 	-
 		class: PHPStan\Type\Doctrine\EntityRepositoryDynamicReturnTypeExtension
 		tags:
diff --git a/src/Type/Doctrine/ObjectManagerMergeDynamicReturnTypeExtension.php b/src/Type/Doctrine/ObjectManagerMergeDynamicReturnTypeExtension.php
new file mode 100644
index 00000000..e562f5f6
--- /dev/null
+++ b/src/Type/Doctrine/ObjectManagerMergeDynamicReturnTypeExtension.php
@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Doctrine;
+
+use PhpParser\Node\Expr\MethodCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Type\Type;
+
+class ObjectManagerMergeDynamicReturnTypeExtension implements \PHPStan\Type\DynamicMethodReturnTypeExtension
+{
+
+	public function getClass(): string
+	{
+		return \Doctrine\Common\Persistence\ObjectManager::class;
+	}
+
+	public function isMethodSupported(MethodReflection $methodReflection): bool
+	{
+		return $methodReflection->getName() === 'merge';
+	}
+
+	public function getTypeFromMethodCall(
+		MethodReflection $methodReflection,
+		MethodCall $methodCall,
+		Scope $scope
+	): Type
+	{
+		if (count($methodCall->args) === 0) {
+			return $methodReflection->getReturnType();
+		}
+
+		return $scope->getType($methodCall->args[0]->value);
+	}
+
+}