diff --git a/tests/PHPStan/Rules/Comparison/data/strict-comparison.php b/tests/PHPStan/Rules/Comparison/data/strict-comparison.php
index 53c9a5ceb3..368aab3305 100644
--- a/tests/PHPStan/Rules/Comparison/data/strict-comparison.php
+++ b/tests/PHPStan/Rules/Comparison/data/strict-comparison.php
@@ -935,3 +935,17 @@ private function returnsVoid(): void
 	}
 
 }
+
+abstract class RandomAbstractClass {}
+
+class AvoidRegressionBecauseThisWasReturningAnErrorInPhpstan11_5
+{
+	private const MAPPING = [\stdClass::class, RandomAbstractClass::class];
+
+	public function test(int $key)
+	{
+		if (is_subclass_of(self::MAPPING[$key], RandomAbstractClass::class) === false) {
+			return;
+		}
+	}
+}