diff --git a/src/ui/flutter_app/android/app/src/main/java/com/calcitem/sanmill/MainActivity.java b/src/ui/flutter_app/android/app/src/main/java/com/calcitem/sanmill/MainActivity.java
index 038de57f..c9b74582 100644
--- a/src/ui/flutter_app/android/app/src/main/java/com/calcitem/sanmill/MainActivity.java
+++ b/src/ui/flutter_app/android/app/src/main/java/com/calcitem/sanmill/MainActivity.java
@@ -95,7 +95,9 @@ public class MainActivity extends FlutterActivity {
 
     @Override
     protected void attachBaseContext(Context base) {
-        super.attachBaseContext(base);
+        if (base != null) {
+            super.attachBaseContext(base);
+        }
 
         // Initialize xCrash.
         if (Build.VERSION.SDK_INT >= 19) {