diff --git a/pyat/at/load/utils.py b/pyat/at/load/utils.py
index 3d0eccddf..ef870af32 100644
--- a/pyat/at/load/utils.py
+++ b/pyat/at/load/utils.py
@@ -112,6 +112,7 @@ def __init__(
     "ringparam": RingParam,
     "wig": elt.Wiggler,
     "matrix66": elt.M66,
+    "M66": elt.M66,
 }
 
 # Map class names to Element classes