diff --git a/hgext/blackbox.py b/hgext/blackbox.py
--- a/hgext/blackbox.py
+++ b/hgext/blackbox.py
@@ -226,7 +226,7 @@
     if not repo.vfs.exists('blackbox.log'):
         return
 
-    limit = opts.get('limit')
+    limit = opts.get(r'limit')
     fp = repo.vfs('blackbox.log', 'r')
     lines = fp.read().split('\n')