--- a/mobile/android/base/java/org/mozilla/gecko/customtabs/IntentUtil.java
+++ b/mobile/android/base/java/org/mozilla/gecko/customtabs/IntentUtil.java
@@ -17,17 +17,17 @@ import android.support.customtabs.Custom
 
 import java.util.ArrayList;
 import java.util.List;
 
 /**
  * A utility class for CustomTabsActivity to extract information from intent.
  * For example, this class helps to extract exit-animation resource id.
  */
-class IntentUtil {
+final class IntentUtil {
 
     public static final int NO_ANIMATION_RESOURCE = -1;
 
     @VisibleForTesting
     @ColorInt
     protected static final int DEFAULT_ACTION_BAR_COLOR = 0xFF363b40; // default color to match design
 
     // Hidden constant values from ActivityOptions.java