diff --git a/.github/workflows/e2e-tests.yml b/.github/workflows/e2e-tests.yml
index 6a8715514db..8f04dffa1ae 100644
--- a/.github/workflows/e2e-tests.yml
+++ b/.github/workflows/e2e-tests.yml
@@ -566,7 +566,10 @@ jobs:
                 echo "FAIL: tmp was created by a worker, meaning sys_temp_dir='tmp~1' was incorrectly evaluated to 'tmp'"
                 exit 1
               fi
-
+          - script: |
+              cd e2e/bug-12972b
+              composer install
+              ../../bin/phpstan analyze
     steps:
       - name: Harden the runner (Audit all outbound calls)
         uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
diff --git a/e2e/bug-12972b/.gitignore b/e2e/bug-12972b/.gitignore
new file mode 100644
index 00000000000..3a9875b460f
--- /dev/null
+++ b/e2e/bug-12972b/.gitignore
@@ -0,0 +1,2 @@
+/vendor/
+composer.lock
diff --git a/e2e/bug-12972b/autoloader.php b/e2e/bug-12972b/autoloader.php
new file mode 100644
index 00000000000..aaaae3ef08f
--- /dev/null
+++ b/e2e/bug-12972b/autoloader.php
@@ -0,0 +1,9 @@
+<?php
+
+require_once __DIR__ . '/vendor/autoload.php';
+
+spl_autoload_register(function($class) {
+	if ($class === \other12972\MyClass::class) {
+		throw new LogicException('this should not happen');
+	}
+});
diff --git a/e2e/bug-12972b/composer.json b/e2e/bug-12972b/composer.json
new file mode 100644
index 00000000000..efff03f3e37
--- /dev/null
+++ b/e2e/bug-12972b/composer.json
@@ -0,0 +1,7 @@
+{
+	"autoload": {
+		"classmap": [
+			"src/"
+		]
+	}
+}
diff --git a/e2e/bug-12972b/phpstan.dist.neon b/e2e/bug-12972b/phpstan.dist.neon
new file mode 100644
index 00000000000..2aea4ef34b4
--- /dev/null
+++ b/e2e/bug-12972b/phpstan.dist.neon
@@ -0,0 +1,8 @@
+parameters:
+    level: 9
+
+    paths:
+        - src
+
+    bootstrapFiles:
+        - autoloader.php
diff --git a/e2e/bug-12972b/real-world.php b/e2e/bug-12972b/real-world.php
new file mode 100644
index 00000000000..8333db5fd66
--- /dev/null
+++ b/e2e/bug-12972b/real-world.php
@@ -0,0 +1,6 @@
+<?php
+
+require 'autoloader.php';
+
+$root = new \Foo12972\MyRoot();
+$root->doBar(new \other12972\MyClass());
diff --git a/e2e/bug-12972b/src/folder/file2.php b/e2e/bug-12972b/src/folder/file2.php
new file mode 100644
index 00000000000..d81e18c01b5
--- /dev/null
+++ b/e2e/bug-12972b/src/folder/file2.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Foo12972;
+
+use other12972\MyClass;
+
+class MyRoot {
+	function doBar(MyClass $myClass):void {}
+}
diff --git a/e2e/bug-12972b/src/other/file.php b/e2e/bug-12972b/src/other/file.php
new file mode 100644
index 00000000000..6e280025d1a
--- /dev/null
+++ b/e2e/bug-12972b/src/other/file.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace other12972;
+
+class MyClass {
+	public function doSomething(): int
+	{
+		return 1;
+	}
+}