diff --git a/README.rst b/README.rst
index 4e60db9e4..f5c5e9727 100644
--- a/README.rst
+++ b/README.rst
@@ -76,6 +76,8 @@ What's New?
 in development
 ^^^^^^^^^^^^^^
 
+* Pin ``urllib3`` version to keep compatibility with ``cachecontrol`` and python3.6.
+
 pydoctor 23.4.0
 ^^^^^^^^^^^^^^^
 
diff --git a/setup.cfg b/setup.cfg
index 149598203..6a59fff4f 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -39,6 +39,7 @@ install_requires =
     appdirs
     CacheControl[filecache]
     Twisted
+    urllib3<2
     requests
     astor
     attrs