diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 2e81bdf..f1253b4 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -338,6 +338,8 @@
             <!-- If true, use functionalTextColor instead of ketTextColor to drawing the label on
                  the key -->
             <flag name="followFunctionalTextColor" value="0x80000" />
+            <!-- Keep aspect ratio of key background. -->
+            <flag name="keepBackgroundAspectRatio" value="0x100000" />
             <!-- If true, disable keyHintLabel. -->
             <flag name="disableKeyHintLabel" value="0x40000000" />
             <!-- If true, disable additionalMoreKeys. -->
diff --git a/java/res/values/themes-lxx-dark.xml b/java/res/values/themes-lxx-dark.xml
index 76e9d33..5b26813 100644
--- a/java/res/values/themes-lxx-dark.xml
+++ b/java/res/values/themes-lxx-dark.xml
@@ -114,6 +114,7 @@
         <item name="android:background">@android:color/transparent</item>
         <item name="keyBackground">@drawable/btn_keyboard_key_popup_action_lxx_dark</item>
         <item name="divider">@null</item>
+        <item name="keyLabelFlags">keepBackgroundAspectRatio</item>
     </style>
     <style
         name="SuggestionStripView.LXX_Dark"
diff --git a/java/res/values/themes-lxx-light.xml b/java/res/values/themes-lxx-light.xml
index 5cd8417..f607807 100644
--- a/java/res/values/themes-lxx-light.xml
+++ b/java/res/values/themes-lxx-light.xml
@@ -114,6 +114,7 @@
         <item name="android:background">@android:color/transparent</item>
         <item name="keyBackground">@drawable/btn_keyboard_key_popup_action_lxx_light</item>
         <item name="divider">@null</item>
+        <item name="keyLabelFlags">keepBackgroundAspectRatio</item>
     </style>
     <style
         name="SuggestionStripView.LXX_Light"