diff --git a/src/AdvancedCalculator/Views/MainView.axaml b/src/AdvancedCalculator/Views/MainView.axaml
index 4f4bfdf..a7ef37d 100644
--- a/src/AdvancedCalculator/Views/MainView.axaml
+++ b/src/AdvancedCalculator/Views/MainView.axaml
@@ -40,10 +40,12 @@
                         AutomationProperties.Name="Insert variable"
                         Tag="{Binding}"
                         DataContext="{Binding $parent[UserControl].DataContext}"
+                        x:DataType="vm:MainViewModel"
                         Command="{Binding InsertVariableCommand}"
                         CommandParameter="{Binding Tag.VariableName, RelativeSource={RelativeSource Self}}">
                   <Grid ColumnDefinitions="Auto,*,Auto"
-                        DataContext="{Binding Tag, RelativeSource={RelativeSource AncestorType=Button}}">
+                        DataContext="{Binding Tag, RelativeSource={RelativeSource AncestorType=Button}}"
+                        x:DataType="m:VariableItem">
                     <TextBlock Grid.Column="0" FontFamily="{StaticResource MDI}"
                                FontSize="{DynamicResource IconSizeM}" Text="{Binding Icon}" VerticalAlignment="Center" Margin="0,0,8,0" />
                     <TextBlock Grid.Column="1" Text="{Binding VariableName}" FontWeight="Bold" VerticalAlignment="Center" />
@@ -73,10 +75,12 @@
                         AutomationProperties.Name="Insert function"
                         Tag="{Binding}"
                         DataContext="{Binding $parent[UserControl].DataContext}"
+                        x:DataType="vm:MainViewModel"
                         Command="{Binding InsertFunctionCommand}"
                         CommandParameter="{Binding Tag.FunctionName, RelativeSource={RelativeSource Self}}">
                   <StackPanel Spacing="8"
-                              DataContext="{Binding Tag, RelativeSource={RelativeSource AncestorType=Button}}">
+                              DataContext="{Binding Tag, RelativeSource={RelativeSource AncestorType=Button}}"
+                              x:DataType="m:FunctionDefinitionItem">
                     <StackPanel Orientation="Horizontal" Spacing="8" VerticalAlignment="Center">
                       <TextBlock FontFamily="{StaticResource MDI}" Text="{Binding Icon}" />
                       <TextBlock Text="{Binding FunctionName}" FontWeight="Bold" />