diff --git a/doc/build.py b/doc/build.py
index a7449c04..31ff1c30 100755
--- a/doc/build.py
+++ b/doc/build.py
@@ -76,7 +76,7 @@ def build_docs(version='dev'):
                           FMT_USE_USER_DEFINED_LITERALS=1 \
                           FMT_API=
       EXCLUDE_SYMBOLS   = fmt::internal::* StringValue write_str
-    '''.format(os.path.dirname(doc_dir)).encode('UTF-8'))
+    '''.format(os.path.join(os.path.dirname(doc_dir), 'cppformat')).encode('UTF-8'))
   if p.returncode != 0:
     raise CalledProcessError(p.returncode, cmd)
   check_call(['sphinx-build',