diff --git a/apax/nodes/md.py b/apax/nodes/md.py
index 58a052bb..d1713b37 100644
--- a/apax/nodes/md.py
+++ b/apax/nodes/md.py
@@ -36,7 +36,7 @@ class ApaxJaxMD(zntrack.Node):
     data_id: int = zntrack.params(-1)
 
     model: ApaxBase = zntrack.deps()
-    repeat: None|int|tuple[int, int, int] = zntrack.params(None)
+    repeat: None | int | tuple[int, int, int] = zntrack.params(None)
 
     config: str = zntrack.params_path(None)