diff --git a/requirements_dev.txt b/requirements_dev.txt
index 71bb88387..b81091323 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -4,7 +4,7 @@ bump2version==1.0.*
 flake8==4.*
 coverage==6.*
 pytest>=5.3.5
-Sphinx==4.*
+Sphinx==3.3.0
 twine==3.*
 black==22.1.0
 pre-commit
@@ -14,4 +14,9 @@ isort
 pytest-benchmark
 pyte
 freezegun==1.*
-pexpect
\ No newline at end of file
+pexpect
+certifi>=2023.7.22 # not directly required, pinned by Snyk to avoid a vulnerability
+jinja2>=3.1.3 # not directly required, pinned by Snyk to avoid a vulnerability
+pygments>=2.15.0 # not directly required, pinned by Snyk to avoid a vulnerability
+requests>=2.31.0 # not directly required, pinned by Snyk to avoid a vulnerability
+setuptools>=65.5.1 # not directly required, pinned by Snyk to avoid a vulnerability
\ No newline at end of file