diff --git a/tests/AssertAnnotationTest.php b/tests/AssertAnnotationTest.php
index 54daaa34486..ade990073f5 100644
--- a/tests/AssertAnnotationTest.php
+++ b/tests/AssertAnnotationTest.php
@@ -2336,7 +2336,7 @@ function assertBIsOne(A $arg): bool
                     /** @param 1 $_arg */
                     function takesOne(int $_arg): void {}
                 ',
-                'error_message' => 'ImpureFunctionCall - src/somefile.php:10:40',
+                'error_message' => 'ImpureFunctionCall - src' . DIRECTORY_SEPARATOR . 'somefile.php:10:40',
             ],
         ];
     }