diff --git a/arbdmodel/__init__.py b/arbdmodel/__init__.py
index 8bf8f7a7be7a7c48fa20ebc50b35e6f13c4e5690..92abb73aa8c921bbbd365097888c801317f81d36 100644
--- a/arbdmodel/__init__.py
+++ b/arbdmodel/__init__.py
@@ -429,6 +429,10 @@ class PointParticle(Transformable, Child):
             resid = p.resid
         except:
             resid = p.idx+1
+        try:
+            mass = p.mass
+        except:
+            mass = 1
 
         try:
             occ = p.occupancy
@@ -447,7 +451,7 @@ class PointParticle(Transformable, Child):
                     idx = p.idx+1,
                     type = p.type_.name[:7],
                     charge = p.charge,
-                    mass = p.mass,
+                    mass = mass,
                     occupancy = occ,
                     beta = beta
                 )