diff --git a/constants.py b/constants.py
index 8e1d9cd..81f0623 100644
--- a/constants.py
+++ b/constants.py
@@ -24,7 +24,8 @@ DEPRECATED = {
     r'\Tens': r'\tensor',
     r'\ann': r'\Ann',
     r'\Id': r'\id',
-    r'\cat': r'\mathcat'
+    r'\cat': r'\mathcat',
+    r'\ob': r'\Ob',
 }
 
 UNICODE = {