diff --git a/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/CheckBox.xaml b/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/CheckBox.xaml
index a27363c48b1..08ef36cd7fc 100644
--- a/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/CheckBox.xaml
+++ b/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/CheckBox.xaml
@@ -11,7 +11,7 @@
 <ResourceDictionary
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:system="clr-namespace:System;assembly=mscorlib"
+    xmlns:sys="clr-namespace:System;assembly=mscorlib"
     xmlns:controls="clr-namespace:System.Windows.Controls;assembly=PresentationFramework">
 
     <Color x:Key="FallbackColor">#FFFF0000</Color>
@@ -19,11 +19,11 @@
     <Thickness x:Key="CheckBoxPadding">11,5,11,6</Thickness>
     <Thickness x:Key="CheckBoxBorderThemeThickness">1</Thickness>
     <Thickness x:Key="CheckBoxContentMargin">8,0,0,0</Thickness>
-    <system:Double x:Key="CheckBoxIconSize">14</system:Double>
-    <system:Double x:Key="CheckBoxHeight">22</system:Double>
-    <system:Double x:Key="CheckBoxWidth">22</system:Double>
-    <system:String x:Key="CheckBoxCheckedGlyph">&#xE73E;</system:String>
-    <system:String x:Key="CheckBoxIndeterminateGlyph">&#xE9AE;</system:String>
+    <sys:Double x:Key="CheckBoxIconSize">14</sys:Double>
+    <sys:Double x:Key="CheckBoxHeight">22</sys:Double>
+    <sys:Double x:Key="CheckBoxWidth">22</sys:Double>
+    <sys:String x:Key="CheckBoxCheckedGlyph">&#xE73E;</sys:String>
+    <sys:String x:Key="CheckBoxIndeterminateGlyph">&#xE9AE;</sys:String>
 
     <Style x:Key="DefaultCheckBoxStyle" TargetType="{x:Type CheckBox}">
         <!--  Universal WPF UI focus  -->
diff --git a/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/DatePicker.xaml b/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/DatePicker.xaml
index 9ed1762dd9f..c6294eaca6f 100644
--- a/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/DatePicker.xaml
+++ b/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/DatePicker.xaml
@@ -11,7 +11,7 @@
 <ResourceDictionary
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:system="clr-namespace:System;assembly=mscorlib">
+    xmlns:sys="clr-namespace:System;assembly=mscorlib">
 
     <Thickness x:Key="DatePickerBorderThemeThickness">1,1,1,0</Thickness>
     <Thickness x:Key="DatePickerAccentBorderThemeThickness">0,0,0,1</Thickness>
@@ -19,9 +19,9 @@
     <Thickness x:Key="DatePickerRightIconMargin">0,8,10,0</Thickness>
     <Thickness x:Key="DatePickerCalendarButtonMargin">0,5,4,0</Thickness>
     <Thickness x:Key="DatePickerCalendarButtonPadding">0,0,0,0</Thickness>
-    <system:Double x:Key="DatePickerCalendarButtonHeight">24</system:Double>
-    <system:Double x:Key="DatePickerCalendarButtonIconSize">14</system:Double>
-    <system:String x:Key="CalendarGlyph">&#xE787;</system:String>
+    <sys:Double x:Key="DatePickerCalendarButtonHeight">24</sys:Double>
+    <sys:Double x:Key="DatePickerCalendarButtonIconSize">14</sys:Double>
+    <sys:String x:Key="CalendarGlyph">&#xE787;</sys:String>
 
     <Style x:Key="DefaultDatePickerTextBoxStyle" TargetType="{x:Type DatePickerTextBox}">
         <Setter Property="FocusVisualStyle" Value="{DynamicResource DefaultControlFocusVisualStyle}" />
diff --git a/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/PasswordBox.xaml b/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/PasswordBox.xaml
index 60155baf871..4216c615c35 100644
--- a/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/PasswordBox.xaml
+++ b/src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/PasswordBox.xaml
@@ -11,7 +11,7 @@
 <ResourceDictionary
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:system="clr-namespace:System;assembly=mscorlib">
+    xmlns:sys="clr-namespace:System;assembly=mscorlib">
 
     <Thickness x:Key="PasswordBoxBorderThemeThickness">1,1,1,1</Thickness>
     <Thickness x:Key="PasswordBoxAccentBorderThemeThickness">0,0,0,1</Thickness>
@@ -19,8 +19,8 @@
     <Thickness x:Key="PasswordBoxRightIconMargin">0,8,10,0</Thickness>
     <Thickness x:Key="PasswordBoxButtonMargin">0,5,4,0</Thickness>
     <Thickness x:Key="PasswordBoxButtonPadding">0,0,0,0</Thickness>
-    <system:Double x:Key="PasswordBoxButtonHeight">24</system:Double>
-    <system:Double x:Key="PasswordBoxButtonIconSize">14</system:Double>
+    <sys:Double x:Key="PasswordBoxButtonHeight">24</sys:Double>
+    <sys:Double x:Key="PasswordBoxButtonIconSize">14</sys:Double>
 
     <ContextMenu x:Key="DefaultPasswordBoxContextMenu">
         <MenuItem Command="ApplicationCommands.Paste" />