diff --git a/MaterialDesignThemes.Wpf/BundledTheme.cs b/MaterialDesignThemes.Wpf/BundledTheme.cs
index c102173ce7..7c9400516c 100644
--- a/MaterialDesignThemes.Wpf/BundledTheme.cs
+++ b/MaterialDesignThemes.Wpf/BundledTheme.cs
@@ -3,7 +3,7 @@
 
 namespace MaterialDesignThemes.Wpf
 {
-    public class BundledTheme : ResourceDictionary
+    public class BundledTheme : ResourceDictionary, IMaterialDesignThemeDictionary
     {
         private BaseTheme? _baseTheme;
         public BaseTheme? BaseTheme
diff --git a/MaterialDesignThemes.Wpf/CustomColorTheme.cs b/MaterialDesignThemes.Wpf/CustomColorTheme.cs
index 3dd1f86d4c..11cf8a1a0d 100644
--- a/MaterialDesignThemes.Wpf/CustomColorTheme.cs
+++ b/MaterialDesignThemes.Wpf/CustomColorTheme.cs
@@ -3,7 +3,7 @@
 
 namespace MaterialDesignThemes.Wpf
 {
-    public class CustomColorTheme : ResourceDictionary
+    public class CustomColorTheme : ResourceDictionary, IMaterialDesignThemeDictionary
     {
         private BaseTheme? _baseTheme;
         public BaseTheme? BaseTheme
diff --git a/MaterialDesignThemes.Wpf/IMaterialDesignThemeDictionary.cs b/MaterialDesignThemes.Wpf/IMaterialDesignThemeDictionary.cs
new file mode 100644
index 0000000000..3fa7e12d12
--- /dev/null
+++ b/MaterialDesignThemes.Wpf/IMaterialDesignThemeDictionary.cs
@@ -0,0 +1,5 @@
+namespace MaterialDesignThemes.Wpf
+{
+    public interface IMaterialDesignThemeDictionary
+    { }
+}
\ No newline at end of file
diff --git a/MaterialDesignThemes.Wpf/PaletteHelper.cs b/MaterialDesignThemes.Wpf/PaletteHelper.cs
index 7706eadf32..ba99b6406d 100644
--- a/MaterialDesignThemes.Wpf/PaletteHelper.cs
+++ b/MaterialDesignThemes.Wpf/PaletteHelper.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Windows;
 
 namespace MaterialDesignThemes.Wpf
@@ -8,23 +9,28 @@ public class PaletteHelper
         public virtual ITheme GetTheme()
         {
             if (Application.Current is null)
-                throw new InvalidOperationException("Cannot get theme outside of a WPF application. Use ResourceDictionaryExtensions.GetTheme on the appropriate resource dictionary instead.");
-            return Application.Current.Resources.GetTheme();
+                throw new InvalidOperationException($"Cannot get theme outside of a WPF application. Use {nameof(ResourceDictionaryExtensions)}.{nameof(ResourceDictionaryExtensions.GetTheme)} on the appropriate resource dictionary instead.");
+            return GetResourceDictionary().GetTheme();
         }
 
         public virtual void SetTheme(ITheme theme)
         {
             if (theme is null) throw new ArgumentNullException(nameof(theme));
             if (Application.Current is null)
-                throw new InvalidOperationException("Cannot set theme outside of a WPF application. Use ResourceDictionaryExtensions.SetTheme on the appropriate resource dictionary instead.");
-            Application.Current.Resources.SetTheme(theme);
+                throw new InvalidOperationException($"Cannot set theme outside of a WPF application. Use {nameof(ResourceDictionaryExtensions)}.{nameof(ResourceDictionaryExtensions.SetTheme)} on the appropriate resource dictionary instead.");
+
+            GetResourceDictionary().SetTheme(theme);
         }
 
         public virtual IThemeManager? GetThemeManager()
         {
             if (Application.Current is null)
-                throw new InvalidOperationException("Cannot get ThemeManager. Use ResourceDictionaryExtensions.GetThemeManager on the appropriate resource dictionary instead.");
-            return Application.Current.Resources.GetThemeManager();
+                throw new InvalidOperationException($"Cannot get ThemeManager outside of a WPF application. Use {nameof(ResourceDictionaryExtensions)}.{nameof(ResourceDictionaryExtensions.GetThemeManager)} on the appropriate resource dictionary instead.");
+            return GetResourceDictionary().GetThemeManager();
         }
+
+        private static ResourceDictionary GetResourceDictionary()
+            => Application.Current.Resources.MergedDictionaries.FirstOrDefault(x => x is IMaterialDesignThemeDictionary) ??
+                Application.Current.Resources;
     }
 }