chop off slash
diff --git a/Doc/conf.py b/Doc/conf.py
index 01ef737..1bb8e50 100644
--- a/Doc/conf.py
+++ b/Doc/conf.py
@@ -47,7 +47,7 @@
 ]
 
 # Ignore .rst in Sphinx its self.
-exclude_trees = ['tools/sphinx/']
+exclude_trees = ['tools/sphinx']
 
 # Relative filename of the reference count data file.
 refcount_file = 'data/refcounts.dat'