diff --git a/src/sage_docbuild/__main__.py b/src/sage_docbuild/__main__.py
index 0d15808a69c..acfcb8392a0 100644
--- a/src/sage_docbuild/__main__.py
+++ b/src/sage_docbuild/__main__.py
@@ -1,3 +1,4 @@
+# sage.doctest: needs sphinx
 r"""
 Sage docbuild main
 
diff --git a/src/sage_docbuild/builders.py b/src/sage_docbuild/builders.py
index a43fdda7350..0be43be307f 100644
--- a/src/sage_docbuild/builders.py
+++ b/src/sage_docbuild/builders.py
@@ -1,3 +1,4 @@
+# sage.doctest: needs sphinx
 """
 Documentation builders
 
diff --git a/src/sage_docbuild/sphinxbuild.py b/src/sage_docbuild/sphinxbuild.py
index 5ae1d2e6b10..6d5823934b8 100644
--- a/src/sage_docbuild/sphinxbuild.py
+++ b/src/sage_docbuild/sphinxbuild.py
@@ -1,4 +1,4 @@
-# -*- coding: utf-8 -*-
+# sage.doctest: needs sphinx
 r"""
 Sphinx build script