diff --git a/Doc/conf.py b/Doc/conf.py
index 01ef7370539..1bb8e508232 100644
--- a/Doc/conf.py
+++ b/Doc/conf.py
@@ -47,7 +47,7 @@ unused_docs = [
 ]
 
 # 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'