diff --git a/src/plone/app/theming/browser/controlpanel.pt b/src/plone/app/theming/browser/controlpanel.pt
index c296300b..fc8db973 100644
--- a/src/plone/app/theming/browser/controlpanel.pt
+++ b/src/plone/app/theming/browser/controlpanel.pt
@@ -460,7 +460,7 @@
                     <div
                         tal:define="error errors/hostnameBlacklist | nothing;
                                     hostnameBlacklist view/theme_settings/hostnameBlacklist | python:[];
-                                    hostnameBlacklist python:request.get('hostnameBlacklist', hostnameBlacklist)"
+                                    hostnameBlacklist python: view.hostname_blacklist or hostnameBlacklist"
                         tal:attributes="class python:'field error' if error else 'field'">
 
                         <label for="hostnameBlacklist" i18n:translate="label_hostname_blacklist">Unthemed host names</label>
@@ -481,7 +481,7 @@
                             id="hostnameBlacklist"
                             rows="5"
                             cols="50"
-                            tal:content="python:'\n'.join(hostnameBlacklist)"
+                            tal:content="python: '\n'.join(hostnameBlacklist)"
                             ></textarea>
 
                     </div>
diff --git a/src/plone/app/theming/browser/controlpanel.py b/src/plone/app/theming/browser/controlpanel.py
index 1eadd675..a9d39abc 100644
--- a/src/plone/app/theming/browser/controlpanel.py
+++ b/src/plone/app/theming/browser/controlpanel.py
@@ -51,6 +51,11 @@ def site_url(self):
         """
         return getSite().absolute_url()
 
+    @property
+    def hostname_blacklist(self):
+        hostname_blacklist = self.request.get('hostnameBlacklist', [])
+        return [host.decode() for host in hostname_blacklist]
+
     def __call__(self):
         self.pskin = getToolByName(self.context, 'portal_skins')
 
@@ -165,8 +170,6 @@ def update(self):
             prefix = form.get('absolutePrefix', None)
             doctype = str(form.get('doctype', ""))
 
-            hostnameBlacklist = form.get('hostnameBlacklist', [])
-
             parameterExpressions = {}
             parameterExpressionsList = form.get('parameterExpressions', [])
 
@@ -200,8 +203,7 @@ def update(self):
                 self.theme_settings.rules = rules
                 self.theme_settings.absolutePrefix = prefix
                 self.theme_settings.parameterExpressions = parameterExpressions
-                self.theme_settings.hostnameBlacklist = [
-                    str(bl) for bl in hostnameBlacklist]
+                self.theme_settings.hostnameBlacklist = self.hostname_blacklist
                 self.theme_settings.custom_css = str(custom_css)
                 self.theme_settings.doctype = doctype