diff --git a/cool_seq_tool/data_sources/feature_overlap.py b/cool_seq_tool/data_sources/feature_overlap.py
index c97f7279..3ac203f4 100644
--- a/cool_seq_tool/data_sources/feature_overlap.py
+++ b/cool_seq_tool/data_sources/feature_overlap.py
@@ -159,7 +159,7 @@ def get_grch38_mane_gene_cds_overlap(
         # Convert residue to inter-residue
         if residue_mode == ResidueMode.RESIDUE:
             if start == end:
-                start -= 1
+                end -= 1
 
             start -= 1