diff --git a/app/src/main/res/layout/content_main.xml b/app/src/main/res/layout/content_main.xml
index 8ec90c2dc..f54ac79f1 100644
--- a/app/src/main/res/layout/content_main.xml
+++ b/app/src/main/res/layout/content_main.xml
@@ -35,6 +35,7 @@
           app:layout_constraintTop_toTopOf="parent"
           />
 
+      <!-- constraintRight_toRightOf is used as android:layoutDirection is supported from API 17 -->
       <androidx.appcompat.widget.AppCompatButton
           android:id="@+id/content_main_card_download_button"
           android:layout_width="wrap_content"