diff --git a/CHANGELIST.md b/CHANGELIST.md
index 593bc69e..4535b8a7 100644
--- a/CHANGELIST.md
+++ b/CHANGELIST.md
@@ -17,6 +17,7 @@
 - Not building against .NET Standard
 - Move RedumpSystemComboBoxItem
 - Move Constants
+- Move WPFCustomMessageBox
 
 ### 2.6.3 (2023-08-15)
 
diff --git a/MPF/External/WPFCustomMessageBox/CustomMessageBox.cs b/MPF.UI.Core/External/WPFCustomMessageBox/CustomMessageBox.cs
similarity index 100%
rename from MPF/External/WPFCustomMessageBox/CustomMessageBox.cs
rename to MPF.UI.Core/External/WPFCustomMessageBox/CustomMessageBox.cs
diff --git a/MPF/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml b/MPF.UI.Core/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml
similarity index 100%
rename from MPF/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml
rename to MPF.UI.Core/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml
diff --git a/MPF/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml.cs b/MPF.UI.Core/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml.cs
similarity index 100%
rename from MPF/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml.cs
rename to MPF.UI.Core/External/WPFCustomMessageBox/CustomMessageBoxWindow.xaml.cs
diff --git a/MPF/External/WPFCustomMessageBox/LICENSE b/MPF.UI.Core/External/WPFCustomMessageBox/LICENSE
similarity index 100%
rename from MPF/External/WPFCustomMessageBox/LICENSE
rename to MPF.UI.Core/External/WPFCustomMessageBox/LICENSE
diff --git a/MPF/External/WPFCustomMessageBox/Util.cs b/MPF.UI.Core/External/WPFCustomMessageBox/Util.cs
similarity index 100%
rename from MPF/External/WPFCustomMessageBox/Util.cs
rename to MPF.UI.Core/External/WPFCustomMessageBox/Util.cs