diff --git a/tests/helpers.py b/tests/helpers.py
index 219fe40..54bb206 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -45,7 +45,7 @@ def chdir(d: Path, *, mkdir: bool = False):
     if not d.exists():
         if not mkdir:
             raise ValueError(f"Directory '{d}' does not exist and we won't create it")
-    elif not d.is_dir():
+    elif not d.isdir():
         raise ValueError(f"'{d}' exists and is not a directory")
 
     prev_wd = Path.cwd()