diff --git a/requirements-dev.txt b/requirements-dev.txt
index ed986a81..7f52ab36 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,4 +1,8 @@
 # TODO: avoids an issue with hanging forever in tests (CORESERV-12009).
+# Inclusion of rfc3339-validator here is a workaround for an issue where
+# pip is not installing this package (defined by `jsonschema[format-nongpl]`).
+# This issue sounds similar to https://github.com/pypa/pip/issues/3903, but
+# that was fixed in pip 20.3 and we're still seeing this issue on 22.0.2.
 jsonschema<4
 mock
 mypy
@@ -7,6 +11,7 @@ pre-commit
 pytest
 pytest-benchmark[histogram]
 pytest-cov
+rfc3339-validator
 types-mock
 types-python-dateutil
 types-pytz
diff --git a/setup.py b/setup.py
index 9795b8ed..4acbc185 100755
--- a/setup.py
+++ b/setup.py
@@ -40,7 +40,7 @@
     ],
     install_requires=[
         "jsonref",
-        "jsonschema[format]>=2.5.1",
+        "jsonschema[format-nogpl]>=2.5.1",
         "python-dateutil",
         "pyyaml",
         'requests',