diff --git a/doc/Pipfile b/doc/Pipfile
index f938473faa4..42a9f5ad514 100644
--- a/doc/Pipfile
+++ b/doc/Pipfile
@@ -22,7 +22,16 @@ verify_ssl = true
 [dev-packages]
 
 [packages]
-sphinx = "2.0.1"
+
+# The latest 4.x sphinx release, currently 4.0.2, fails `make html`.  For
+# details, see: https://github.com/apache/trafficserver/issues/7938
+#
+# The 3.x releases build fine, however. So we currently pin to that.
+#
+# Once that issue, either with sphinx or our docs, is resolved, then we should
+# unpin sphinx by setting the following to "*".
+sphinx = "==3.*"
+
 sphinx-rtd-theme = "*"
 sphinxcontrib-plantuml = "*"
 # i18n
diff --git a/doc/ext/traffic-server.py b/doc/ext/traffic-server.py
index 20336945ad8..89b80d6179e 100644
--- a/doc/ext/traffic-server.py
+++ b/doc/ext/traffic-server.py
@@ -31,7 +31,7 @@
 from docutils.parsers.rst import directives
 from sphinx.domains import Domain, ObjType, std
 from sphinx.roles import XRefRole
-from sphinx.locale import l_, _
+from sphinx.locale import _
 import sphinx
 
 import subprocess