diff --git a/neatnet/artifacts.py b/neatnet/artifacts.py
index 7309a4e..6a190a6 100644
--- a/neatnet/artifacts.py
+++ b/neatnet/artifacts.py
@@ -1073,10 +1073,6 @@ def nx_gx(
     # correctly pick-up the highest hierarchy and drop all lower
     if artifact.C > 0:
         logger.debug("HIGHEST C")
-        # define mask for E and S strokes
-        es_mask = edges.coins_group.isin(all_ends.coins_group)
-        # filter Cs
-        highest_hierarchy = edges[~es_mask]
     else:
         logger.debug("HIGHEST E")
         singles = set()
@@ -1089,12 +1085,14 @@ def nx_gx(
             ):
                 singles.add(group)
                 visited.append(group)
-        # filter ends
+        # re-filter ends
         all_ends = edges[edges.coins_group.isin(singles)]
-        # define mask for E and S strokes
-        es_mask = edges.coins_group.isin(all_ends.coins_group)
-        # filter Cs
-        highest_hierarchy = edges[~es_mask]
+
+    # define mask for E and S strokes
+    es_mask = edges.coins_group.isin(all_ends.coins_group)
+
+    # filter Cs
+    highest_hierarchy = edges[~es_mask]
 
     # get nodes forming the artifact
     relevant_nodes = nodes.iloc[