diff --git a/saqc/funcs/tools.py b/saqc/funcs/tools.py
index db4b3700af72d4492134d3537fe384e7684ddf8e..e0f53fabbc32a8b6a89c2d0af1a68267f1dfc565 100644
--- a/saqc/funcs/tools.py
+++ b/saqc/funcs/tools.py
@@ -503,8 +503,9 @@ class ToolsMixin:
             and not isinstance(yscope[0], (list, tuple))
         ):
             yscope = tuple(yscope)
+        if yscope is not None:
 
-        ax_kwargs.update({"ylim": yscope})
+            ax_kwargs.update({"ylim": yscope})
 
         if not path:
             mpl.use(_MPL_DEFAULT_BACKEND)