diff --git a/src/requirements.in b/src/requirements.in
index 416102a3..de9a0886 100644
--- a/src/requirements.in
+++ b/src/requirements.in
@@ -1,4 +1,4 @@
 beautifulsoup4
 invoke
-pelican[markdown]
+pelican[markdown]==4.2.0
 pelican-series-plugin
diff --git a/src/requirements.txt b/src/requirements.txt
index c69f472e..70c97b69 100644
--- a/src/requirements.txt
+++ b/src/requirements.txt
@@ -16,13 +16,13 @@ invoke==1.5.0
     # via -r requirements.in
 jinja2==2.11.3
     # via pelican
-markdown==3.3.4
+markdown==3.1.1
     # via pelican
 markupsafe==1.1.1
     # via jinja2
 pelican-series-plugin==1.1.1
     # via -r requirements.in
-pelican[markdown]==4.6.0
+pelican[markdown]==4.2.0
     # via
     #   -r requirements.in
     #   pelican-series-plugin
@@ -37,8 +37,12 @@ pytz==2021.1
 six==1.15.0
     # via
     #   feedgenerator
+    #   pelican
     #   python-dateutil
 soupsieve==2.2.1
     # via beautifulsoup4
 unidecode==1.2.0
     # via pelican
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools