diff --git a/src/modules/imageresizer/tests/Properties/AppFixture.cs b/src/modules/imageresizer/tests/Properties/AppFixture.cs
index 2361b76af4..433a869cb1 100644
--- a/src/modules/imageresizer/tests/Properties/AppFixture.cs
+++ b/src/modules/imageresizer/tests/Properties/AppFixture.cs
@@ -26,6 +26,7 @@ namespace ImageResizer.Properties
             {
                 if (disposing)
                 {
+                    _imageResizerApp.Dispose();
                     _imageResizerApp = null;
                 }
 
diff --git a/src/modules/imageresizer/ui/ImageResizerUI.csproj b/src/modules/imageresizer/ui/ImageResizerUI.csproj
index 54fb3f17be..2d95951209 100644
--- a/src/modules/imageresizer/ui/ImageResizerUI.csproj
+++ b/src/modules/imageresizer/ui/ImageResizerUI.csproj
@@ -61,7 +61,7 @@
     <Resource Include="Resources\ImageResizer.png" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="MahApps.Metro" Version="2.3.3" />
+    <PackageReference Include="ControlzEx" Version="4.4.0" />
     <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="3.3.0">
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
diff --git a/src/modules/imageresizer/ui/Themes/Dark.xaml b/src/modules/imageresizer/ui/Themes/Dark.xaml
index 7baf11213e..f0d0cb1339 100644
--- a/src/modules/imageresizer/ui/Themes/Dark.xaml
+++ b/src/modules/imageresizer/ui/Themes/Dark.xaml
@@ -1,11 +1,6 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:markup="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:markupWithAssembly="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-                    xmlns:options="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
-                    xmlns:system="clr-namespace:System;assembly=System.Runtime"
-                    mc:Ignorable="options">
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime">
 
     <!--  Metadata  -->
     <system:String x:Key="Theme.Name">Dark.Accent1</system:String>
diff --git a/src/modules/imageresizer/ui/Themes/HighContrast1.xaml b/src/modules/imageresizer/ui/Themes/HighContrast1.xaml
index 123c3aa845..7bfaf2e19d 100644
--- a/src/modules/imageresizer/ui/Themes/HighContrast1.xaml
+++ b/src/modules/imageresizer/ui/Themes/HighContrast1.xaml
@@ -1,11 +1,6 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:markup="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:markupWithAssembly="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-                    xmlns:options="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
-                    xmlns:system="clr-namespace:System;assembly=System.Runtime"
-                    mc:Ignorable="options">
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime">
 
     <!--  Metadata  -->
     <system:String x:Key="Theme.Name">HighContrast.Accent2</system:String>
diff --git a/src/modules/imageresizer/ui/Themes/HighContrast2.xaml b/src/modules/imageresizer/ui/Themes/HighContrast2.xaml
index 10b162d4d6..15f7f1b639 100644
--- a/src/modules/imageresizer/ui/Themes/HighContrast2.xaml
+++ b/src/modules/imageresizer/ui/Themes/HighContrast2.xaml
@@ -1,11 +1,6 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:markup="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:markupWithAssembly="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-                    xmlns:options="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
-                    xmlns:system="clr-namespace:System;assembly=System.Runtime"
-                    mc:Ignorable="options">
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime">
 
     <!--  Metadata  -->
     <system:String x:Key="Theme.Name">HighContrast.Accent3</system:String>
diff --git a/src/modules/imageresizer/ui/Themes/HighContrastBlack.xaml b/src/modules/imageresizer/ui/Themes/HighContrastBlack.xaml
index 069adbae7c..3f5458dabb 100644
--- a/src/modules/imageresizer/ui/Themes/HighContrastBlack.xaml
+++ b/src/modules/imageresizer/ui/Themes/HighContrastBlack.xaml
@@ -1,12 +1,7 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:markup="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:markupWithAssembly="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-                    xmlns:options="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
-                    xmlns:system="clr-namespace:System;assembly=System.Runtime"
-                    mc:Ignorable="options">
-
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime">
+    
     <!--  Metadata  -->
     <system:String x:Key="Theme.Name">HighContrast.Accent4</system:String>
     <system:String x:Key="Theme.Origin">PowerToysImageResizer</system:String>
diff --git a/src/modules/imageresizer/ui/Themes/HighContrastWhite.xaml b/src/modules/imageresizer/ui/Themes/HighContrastWhite.xaml
index 620ea4f942..b68137fc4b 100644
--- a/src/modules/imageresizer/ui/Themes/HighContrastWhite.xaml
+++ b/src/modules/imageresizer/ui/Themes/HighContrastWhite.xaml
@@ -1,11 +1,6 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:markup="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:markupWithAssembly="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-                    xmlns:options="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
-                    xmlns:system="clr-namespace:System;assembly=System.Runtime"
-                    mc:Ignorable="options">
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime">
 
     <!--  Metadata  -->
     <system:String x:Key="Theme.Name">HighContrast.Accent5</system:String>
diff --git a/src/modules/imageresizer/ui/Themes/Light.xaml b/src/modules/imageresizer/ui/Themes/Light.xaml
index e7d07ca709..3f9323e3a0 100644
--- a/src/modules/imageresizer/ui/Themes/Light.xaml
+++ b/src/modules/imageresizer/ui/Themes/Light.xaml
@@ -1,11 +1,6 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:markup="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:markupWithAssembly="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
-                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-                    xmlns:options="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
-                    xmlns:system="clr-namespace:System;assembly=System.Runtime"
-                    mc:Ignorable="options">
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime">
 
     <!--  Metadata  -->
     <system:String x:Key="Theme.Name">Light.Accent1</system:String>
diff --git a/src/modules/imageresizer/ui/Utilities/CustomLibraryThemeProvider.cs b/src/modules/imageresizer/ui/Utilities/CustomLibraryThemeProvider.cs
new file mode 100644
index 0000000000..ab2fc3a7f5
--- /dev/null
+++ b/src/modules/imageresizer/ui/Utilities/CustomLibraryThemeProvider.cs
@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using ControlzEx.Theming;
+
+namespace ImageResizer.Utilities
+{
+    public class CustomLibraryThemeProvider : LibraryThemeProvider
+    {
+        public static readonly CustomLibraryThemeProvider DefaultInstance = new CustomLibraryThemeProvider();
+
+        public CustomLibraryThemeProvider()
+            : base(true)
+        {
+        }
+
+        /// <inheritdoc />
+        public override void FillColorSchemeValues(Dictionary<string, string> values, RuntimeThemeColorValues colorValues)
+        {
+        }
+    }
+}
diff --git a/src/modules/imageresizer/ui/Utilities/ThemeManager.cs b/src/modules/imageresizer/ui/Utilities/ThemeManager.cs
index 15c47c936f..03efb9688a 100644
--- a/src/modules/imageresizer/ui/Utilities/ThemeManager.cs
+++ b/src/modules/imageresizer/ui/Utilities/ThemeManager.cs
@@ -1,11 +1,11 @@
 // Copyright (c) Microsoft Corporation
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
+
 using System;
 using System.Linq;
 using System.Windows;
 using ControlzEx.Theming;
-using MahApps.Metro.Theming;
 using Microsoft.Win32;
 
 namespace ImageResizer.Utilities
@@ -39,27 +39,27 @@ namespace ImageResizer.Utilities
             ControlzEx.Theming.ThemeManager.Current.AddLibraryTheme(
                 new LibraryTheme(
                     highContrastOneThemeUri,
-                    MahAppsLibraryThemeProvider.DefaultInstance));
+                    CustomLibraryThemeProvider.DefaultInstance));
             ControlzEx.Theming.ThemeManager.Current.AddLibraryTheme(
                 new LibraryTheme(
                     highContrastTwoThemeUri,
-                    MahAppsLibraryThemeProvider.DefaultInstance));
+                    CustomLibraryThemeProvider.DefaultInstance));
             ControlzEx.Theming.ThemeManager.Current.AddLibraryTheme(
                 new LibraryTheme(
                     highContrastBlackThemeUri,
-                    MahAppsLibraryThemeProvider.DefaultInstance));
+                    CustomLibraryThemeProvider.DefaultInstance));
             ControlzEx.Theming.ThemeManager.Current.AddLibraryTheme(
                 new LibraryTheme(
                     highContrastWhiteThemeUri,
-                    MahAppsLibraryThemeProvider.DefaultInstance));
+                    CustomLibraryThemeProvider.DefaultInstance));
             ControlzEx.Theming.ThemeManager.Current.AddLibraryTheme(
                 new LibraryTheme(
                     lightThemeUri,
-                    MahAppsLibraryThemeProvider.DefaultInstance));
+                    CustomLibraryThemeProvider.DefaultInstance));
             ControlzEx.Theming.ThemeManager.Current.AddLibraryTheme(
                 new LibraryTheme(
                     darkThemeUri,
-                    MahAppsLibraryThemeProvider.DefaultInstance));
+                    CustomLibraryThemeProvider.DefaultInstance));
 
             ResetTheme();
             ControlzEx.Theming.ThemeManager.Current.ThemeSyncMode = ThemeSyncMode.SyncWithAppMode;