diff --git a/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php b/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php
index a0d08561d7..f64ac08dd7 100644
--- a/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php
@@ -961,4 +961,18 @@ public function testBug3979(): void
 		$this->analyse([__DIR__ . '/data/bug-3979.php'], []);
 	}
 
+	public function testBug8464(): void
+	{
+		$this->checkAlwaysTrueCheckTypeFunctionCall = true;
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-8464.php'], []);
+	}
+
+	public function testBug8954(): void
+	{
+		$this->checkAlwaysTrueCheckTypeFunctionCall = true;
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-8954.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-8464.php b/tests/PHPStan/Rules/Comparison/data/bug-8464.php
new file mode 100644
index 0000000000..23cd280d7a
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-8464.php
@@ -0,0 +1,18 @@
+<?php // lint >= 8.0
+
+namespace Bug8464;
+
+final class ObjectUtil
+{
+	/**
+	 * @param class-string $type
+	 */
+	public static function instanceOf(mixed $object, string $type): bool
+	{
+		return \is_object($object)
+			&& (
+				$object::class === $type ||
+				is_subclass_of($object, $type)
+			);
+	}
+}
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-8954.php b/tests/PHPStan/Rules/Comparison/data/bug-8954.php
new file mode 100644
index 0000000000..b89b47ba6d
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-8954.php
@@ -0,0 +1,28 @@
+<?php declare(strict_types = 1);
+
+namespace Bug8954;
+
+/**
+ * @template U
+ * @template V
+ *
+ * @param ?class-string<U> $class
+ * @param class-string<V> $expected
+ *
+ * @return ?class-string<V>
+ */
+function ensureSubclassOf(?string $class, string $expected): ?string {
+	if ($class === null) {
+		return $class;
+	}
+
+	if (!class_exists($class)) {
+		throw new \Exception("Class “{$class}” does not exist.");
+	}
+
+	if (!is_subclass_of($class, $expected)) {
+		throw new \Exception("Class “{$class}” is not a subclass of “{$expected}”.");
+	}
+
+	return $class;
+}