diff --git a/src/Rules/FunctionDefinitionCheck.php b/src/Rules/FunctionDefinitionCheck.php
index 50a0c99e85..c49d6ce4ea 100644
--- a/src/Rules/FunctionDefinitionCheck.php
+++ b/src/Rules/FunctionDefinitionCheck.php
@@ -584,15 +584,20 @@ private function getParameterReferencedClasses(ParameterReflection $parameter):
 			return $parameter->getNativeType()->getReferencedClasses();
 		}
 
-		$outTypeClasses = [];
-		if ($parameter->getOutType() !== null && $this->absentTypeChecks) {
-			$outTypeClasses = $parameter->getOutType()->getReferencedClasses();
+		$moreClasses = [];
+		if ($this->absentTypeChecks) {
+			if ($parameter->getOutType() !== null) {
+				$moreClasses = array_merge($moreClasses, $parameter->getOutType()->getReferencedClasses());
+			}
+			if ($parameter->getClosureThisType() !== null) {
+				$moreClasses = array_merge($moreClasses, $parameter->getClosureThisType()->getReferencedClasses());
+			}
 		}
 
 		return array_merge(
 			$parameter->getNativeType()->getReferencedClasses(),
 			$parameter->getPhpDocType()->getReferencedClasses(),
-			$outTypeClasses,
+			$moreClasses,
 		);
 	}
 
diff --git a/tests/PHPStan/Rules/Functions/ExistingClassesInTypehintsRuleTest.php b/tests/PHPStan/Rules/Functions/ExistingClassesInTypehintsRuleTest.php
index 5cbe1c95eb..6dc1acf00c 100644
--- a/tests/PHPStan/Rules/Functions/ExistingClassesInTypehintsRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/ExistingClassesInTypehintsRuleTest.php
@@ -470,4 +470,22 @@ public function testParamOutClasses(): void
 		]);
 	}
 
+	public function testParamClosureThisClasses(): void
+	{
+		$this->analyse([__DIR__ . '/data/param-closure-this-classes.php'], [
+			[
+				'Parameter $a of method ParamClosureThisClasses\Bar::doFoo() has invalid type ParamClosureThisClasses\Nonexistent.',
+				24,
+			],
+			[
+				'Parameter $b of method ParamClosureThisClasses\Bar::doFoo() has invalid type ParamClosureThisClasses\FooTrait.',
+				25,
+			],
+			[
+				'Class ParamClosureThisClasses\Foo referenced with incorrect case: ParamClosureThisClasses\fOO.',
+				26,
+			],
+		]);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/data/param-closure-this-classes.php b/tests/PHPStan/Rules/Functions/data/param-closure-this-classes.php
new file mode 100644
index 0000000000..d1652c132b
--- /dev/null
+++ b/tests/PHPStan/Rules/Functions/data/param-closure-this-classes.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace ParamClosureThisClassesFunctions;
+
+trait FooTrait
+{
+
+}
+
+class Foo
+{
+
+}
+
+/**
+ * @param-closure-this Nonexistent $a
+ * @param-closure-this FooTrait $b
+ * @param-closure-this fOO $c
+ */
+function doFoo(
+	callable $a,
+	callable $b,
+	callable $c
+): void
+{
+
+}
diff --git a/tests/PHPStan/Rules/Methods/ExistingClassesInTypehintsRuleTest.php b/tests/PHPStan/Rules/Methods/ExistingClassesInTypehintsRuleTest.php
index c40ac75233..0d13ec6d87 100644
--- a/tests/PHPStan/Rules/Methods/ExistingClassesInTypehintsRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/ExistingClassesInTypehintsRuleTest.php
@@ -490,4 +490,22 @@ public function testParamOutClasses(): void
 		]);
 	}
 
+	public function testParamClosureThisClasses(): void
+	{
+		$this->analyse([__DIR__ . '/data/param-closure-this-classes.php'], [
+			[
+				'Parameter $a of method ParamClosureThisClasses\Bar::doFoo() has invalid type ParamClosureThisClasses\Nonexistent.',
+				24,
+			],
+			[
+				'Parameter $b of method ParamClosureThisClasses\Bar::doFoo() has invalid type ParamClosureThisClasses\FooTrait.',
+				25,
+			],
+			[
+				'Class ParamClosureThisClasses\Foo referenced with incorrect case: ParamClosureThisClasses\fOO.',
+				26,
+			],
+		]);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Methods/data/param-closure-this-classes.php b/tests/PHPStan/Rules/Methods/data/param-closure-this-classes.php
new file mode 100644
index 0000000000..f36ffbfb1f
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/param-closure-this-classes.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace ParamClosureThisClasses;
+
+trait FooTrait
+{
+
+}
+
+class Foo
+{
+
+}
+
+class Bar
+{
+
+	/**
+	 * @param-closure-this Nonexistent $a
+	 * @param-closure-this FooTrait $b
+	 * @param-closure-this fOO $c
+	 */
+	public function doFoo(
+		callable $a,
+		callable $b,
+		callable $c
+	): void
+	{
+
+	}
+
+}