diff --git a/manifests/apache.pp b/manifests/apache.pp
index b3fec56..de6c501 100644
--- a/manifests/apache.pp
+++ b/manifests/apache.pp
@@ -53,7 +53,7 @@
   ]
 
   $api_additional_request_headers = $pulpcore::api_client_auth_cn_map.map |String $cn, String $pulp_user| {
-    "set ${remote_user_environ_header} \"${pulp_user}\" \"expr=%{SSL_CLIENT_S_DN_CN} == '${cn}'\""
+    "set ${remote_user_environ_header} \"${pulp_user}\" \"expr=%{tolower:SSL_CLIENT_S_DN_CN} == '${cn.downcase}'\""
   }
 
   $api_directory = {
diff --git a/spec/classes/plugin_container_spec.rb b/spec/classes/plugin_container_spec.rb
index fc30726..239e4fa 100644
--- a/spec/classes/plugin_container_spec.rb
+++ b/spec/classes/plugin_container_spec.rb
@@ -52,7 +52,7 @@ class {'pulpcore':
   <Location "/pulpcore_registry/v2/">
     RequestHeader unset REMOTE-USER
     RequestHeader unset REMOTE_USER
-    RequestHeader set REMOTE-USER "admin" "expr=%{SSL_CLIENT_S_DN_CN} == 'foreman.example.com'"
+    RequestHeader set REMOTE-USER "admin" "expr=%{tolower:SSL_CLIENT_S_DN_CN} == 'foreman.example.com'"
     ProxyPass unix:///run/pulpcore-api.sock|http://pulpcore-api/v2/
     ProxyPassReverse unix:///run/pulpcore-api.sock|http://pulpcore-api/v2/
   </Location>
diff --git a/spec/classes/pulpcore_spec.rb b/spec/classes/pulpcore_spec.rb
index 4822c8f..2ecb201 100644
--- a/spec/classes/pulpcore_spec.rb
+++ b/spec/classes/pulpcore_spec.rb
@@ -522,7 +522,7 @@
                 'request_headers' => [
                   'unset REMOTE-USER',
                   'unset REMOTE_USER',
-                  'set REMOTE-USER "admin" "expr=%{SSL_CLIENT_S_DN_CN} == \'foreman.example.com\'"',
+                  'set REMOTE-USER "admin" "expr=%{tolower:SSL_CLIENT_S_DN_CN} == \'foreman.example.com\'"',
                 ],
               }
             ])