diff --git a/src/sage/misc/sphinxify.py b/src/sage/misc/sphinxify.py
index 4849c2bffa..76b7bc8602 100644
--- a/src/sage/misc/sphinxify.py
+++ b/src/sage/misc/sphinxify.py
@@ -25,6 +25,7 @@ from __future__ import absolute_import, print_function
 import os
 import re
 import shutil
+import warnings
 from tempfile import mkdtemp
 from sphinx.application import Sphinx
 
@@ -120,7 +121,10 @@ smart_quotes = no""")
     # buildername, confoverrides, status, warning, freshenv).
     sphinx_app = Sphinx(srcdir, confdir, outdir, doctreedir, format,
                         confoverrides, None, None, True)
-    sphinx_app.build(None, [rst_name])
+    with warnings.catch_warnings():
+        # Quick and dirty workaround for https://trac.sagemath.org/ticket/28856#comment:19
+        warnings.simplefilter("ignore")
+        sphinx_app.build(None, [rst_name])
     sys.path = old_sys_path
 
     # We need to remove "_" from __builtin__ that the gettext module installs