diff --git a/ties/ligand.py b/ties/ligand.py
index 9ef78f3..3257877 100644
--- a/ties/ligand.py
+++ b/ties/ligand.py
@@ -239,7 +239,7 @@ def suffix(self):
 
     def uses_GAFF_atom_names(self):
         assert self.current.suffix.lower() == '.mol2'
-        mol = parmed.load_file('ejm_55.mol2', structure=True)
+        mol = parmed.load_file(str(self.current), structure=True)
         atom_types = {atom.type for atom in mol.atoms}
         if len(atom_types - self.GAFF_ATOM_NAMES) > 0:
             # there are names that are not GAFF atom names