diff --git a/mknodes/templatenodes/mkpipdeptree.py b/mknodes/templatenodes/mkpipdeptree.py
index b8aa2a34..5659b3e9 100644
--- a/mknodes/templatenodes/mkpipdeptree.py
+++ b/mknodes/templatenodes/mkpipdeptree.py
@@ -33,7 +33,7 @@ def get_mermaid(
     # thus ensuring, that the filter will be applied on ReverseTree
     if reverse:
         tree = tree.reverse()
-    show_only = package.split(",") if package and isinstance(package, str) else package
+    show_only = package.split(",") if isinstance(package, str) else package
     exclude_list = set(exclude.split(",")) if exclude else None
     if show_only is not None or exclude_list is not None:
         tree = tree.filter_nodes(show_only, exclude_list)