diff --git a/src/core/atomic/mmcif.py b/src/core/atomic/mmcif.py
index 08ba2366d..68c34cb55 100644
--- a/src/core/atomic/mmcif.py
+++ b/src/core/atomic/mmcif.py
@@ -54,6 +54,9 @@ def open_mmcif(session, path, file_name=None, auto_style=True, coordsets=False,
     models = [StructureClass(session, name=file_name, c_pointer=p, auto_style=auto_style) for p in pointers]
     for m in models:
         m.filename = path
+    import sys
+    for m in models:
+        print(m, sys.getrefcount(m), file=sys.__stderr__)
 
     info = "Opened mmCIF data containing %d atoms%s %d bonds" % (
         sum(m.num_atoms for m in models),