diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index 456c8d6874..fb164df505 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -3181,7 +3181,7 @@ private function enterArrowFunctionWithoutReflection(Expr\ArrowFunction $arrowFu
 			$arrowFunctionScope->nativeExpressionTypes,
 			$arrowFunctionScope->conditionalExpressions,
 			$arrowFunctionScope->inClosureBindScopeClasses,
-			null,
+			new TrivialParametersAcceptor(),
 			true,
 			[],
 			[],
diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
index 73d9e7f373..41f93f60b3 100644
--- a/tests/PHPStan/Analyser/NodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -1123,6 +1123,7 @@ public function dataFileAsserts(): iterable
 
 		if (PHP_VERSION_ID >= 70400) {
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/arrow-function-argument-type.php');
+			yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Functions/data/bug-anonymous-function-method-constant.php');
 		}
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/closure-argument-type.php');
diff --git a/tests/PHPStan/Rules/Functions/ArrowFunctionReturnTypeRuleTest.php b/tests/PHPStan/Rules/Functions/ArrowFunctionReturnTypeRuleTest.php
index 3155b387c2..bf46cd56a6 100644
--- a/tests/PHPStan/Rules/Functions/ArrowFunctionReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/ArrowFunctionReturnTypeRuleTest.php
@@ -65,4 +65,13 @@ public function testBugSpaceship(): void
 		$this->analyse([__DIR__ . '/data/bug-spaceship.php'], []);
 	}
 
+	public function testBugFunctionMethodConstants(): void
+	{
+		if (PHP_VERSION_ID < 70400) {
+			$this->markTestSkipped('Test requires PHP 7.4.');
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-anonymous-function-method-constant.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/ClosureReturnTypeRuleTest.php b/tests/PHPStan/Rules/Functions/ClosureReturnTypeRuleTest.php
index 5fe0446016..a62e35ea03 100644
--- a/tests/PHPStan/Rules/Functions/ClosureReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/ClosureReturnTypeRuleTest.php
@@ -6,6 +6,7 @@
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleLevelHelper;
 use PHPStan\Testing\RuleTestCase;
+use const PHP_VERSION_ID;
 
 /**
  * @extends RuleTestCase<ClosureReturnTypeRule>
@@ -128,4 +129,13 @@ public function testBug7220(): void
 		$this->analyse([__DIR__ . '/data/bug-7220.php'], []);
 	}
 
+	public function testBugFunctionMethodConstants(): void
+	{
+		if (PHP_VERSION_ID < 70400) {
+			$this->markTestSkipped('Test requires PHP 7.4.');
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-anonymous-function-method-constant.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/data/bug-anonymous-function-method-constant.php b/tests/PHPStan/Rules/Functions/data/bug-anonymous-function-method-constant.php
new file mode 100644
index 0000000000..5347b1116f
--- /dev/null
+++ b/tests/PHPStan/Rules/Functions/data/bug-anonymous-function-method-constant.php
@@ -0,0 +1,14 @@
+<?php declare(strict_types = 1); // lint >= 7.4
+
+namespace BugAnonymousFunctionMethodConstant;
+
+$a = fn() => __FUNCTION__;
+$b = fn() => __METHOD__;
+
+$c = function() { return __FUNCTION__; };
+$d = function() { return __METHOD__; };
+
+\PHPStan\Testing\assertType("'{closure}'", $a());
+\PHPStan\Testing\assertType("'{closure}'", $b());
+\PHPStan\Testing\assertType("'{closure}'", $c());
+\PHPStan\Testing\assertType("'{closure}'", $d());