diff --git a/Changelog.md b/Changelog.md
index b09fca57d..52d5d0cd7 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -149,6 +149,7 @@
   - [#439](../../issues/439) - Context menu and submenu disappears after a right click
   - [#446](../../issues/446) - Wrong submenu Position in application menu
   - [#450](../../issues/450) - Fix Ribbon.OnTitleBarChanged clearing the new title bar instead of the old one (thanks @Cubey2019)
+  - [#451](../../issues/451) - combobox and dateformat
   - [#454](../../issues/454) - RibbonWindow title not shown in correct position when using SizeToContent
   - [#457](../../issues/457) - Using the keytip shortcut to open a backstage briefly opens it, then closes it immediately
   - [#459](../../issues/459) - Label of the Spinner disappears, if there isn't enough place
diff --git a/Fluent.Ribbon/Themes/Controls/ComboBox.xaml b/Fluent.Ribbon/Themes/Controls/ComboBox.xaml
index 21ec0421d..caf9534ec 100644
--- a/Fluent.Ribbon/Themes/Controls/ComboBox.xaml
+++ b/Fluent.Ribbon/Themes/Controls/ComboBox.xaml
@@ -168,6 +168,7 @@
                                           Content="{TemplateBinding SelectionBoxItem}"
                                           ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
                                           ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
+                                          ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}"
                                           VerticalAlignment="Center"
                                           HorizontalAlignment="Left" />
                         <Image Margin="0"