diff --git a/manifests/defaults.pp b/manifests/defaults.pp
index 69f210bf..f2539377 100644
--- a/manifests/defaults.pp
+++ b/manifests/defaults.pp
@@ -5,4 +5,11 @@
 # This file is loaded in the params.pp of each class.
 #
 class openstacklib::defaults {
+
+  # TODO(tobias-urdin): Remove this in the T release when we remove
+  # all Puppet 4 related code.
+  if versioncmp($::puppetversion, '5.0.0') < 0 {
+    warning('OpenStack modules support for Puppet 4 is deprecated \
+and will be officially unsupported in the T release')
+  }
 }
diff --git a/releasenotes/notes/deprecate-puppet4-59a430de68834017.yaml b/releasenotes/notes/deprecate-puppet4-59a430de68834017.yaml
new file mode 100644
index 00000000..fb5d6982
--- /dev/null
+++ b/releasenotes/notes/deprecate-puppet4-59a430de68834017.yaml
@@ -0,0 +1,8 @@
+---
+prelude: >
+    Puppet OpenStack has in this release deprecated Puppet 4 support.
+    This older version of Puppet is EOL since October 2018 and will only
+    get security fixes. We will continue to support this Puppet version
+    for the duration of this release with minimal testing. In the next
+    release Puppet 4 support will be removed completely and you should
+    move to using Puppet 5 or the newly released Puppet 6.