diff --git a/rmgpy/data/solvation.py b/rmgpy/data/solvation.py
index 6e30e40a28..45a133de01 100644
--- a/rmgpy/data/solvation.py
+++ b/rmgpy/data/solvation.py
@@ -1722,7 +1722,7 @@ def _add_ring_correction_solute_data_from_tree(self, solute_data, ring_database,
             entry = ring_database.descend_tree(molecule, atoms)
             matched_ring_entries.append(entry)
 
-        if matched_ring_entries is []:
+        if matched_ring_entries == []:
             raise KeyError('Node not found in database.')
         # Decide which group to keep
         is_partial_match = True