diff --git a/deepmd_gnn/mace.py b/deepmd_gnn/mace.py
index 95d9a67..3ea6802 100644
--- a/deepmd_gnn/mace.py
+++ b/deepmd_gnn/mace.py
@@ -177,8 +177,8 @@
 ]
 
 PeriodicTable = {
-    **{ee: ii for ii, ee in enumerate(ELEMENTS)},
-    **{f"m{ee}": ii for ii, ee in enumerate(ELEMENTS)},
+    **{ee: ii + 1 for ii, ee in enumerate(ELEMENTS)},
+    **{f"m{ee}": ii + 1 for ii, ee in enumerate(ELEMENTS)},
     "HW": 1,
     "OW": 8,
 }