diff --git a/cmd/fyne/internal/mobile/gendex/README.md b/cmd/fyne/internal/mobile/gendex/README.md
new file mode 100644
index 0000000000..ce8c7cc830
--- /dev/null
+++ b/cmd/fyne/internal/mobile/gendex/README.md
@@ -0,0 +1,15 @@
+# gendex
+
+## How to run
+
+From project root:
+
+```console
+cd ../../../../cmd/fyne/internal/mobile/
+go run ./gendex
+cd ../../../../
+go install ./cmd/fyne
+```
+
+It will generate the `./cmd/fyne/internal/mobile/dex.go` file
+that will be used in the `fyne` CLI for your next builds.
diff --git a/internal/driver/mobile/app/GoNativeActivity.java b/internal/driver/mobile/app/GoNativeActivity.java
index bb1c9b97c3..5cf9fc1997 100644
--- a/internal/driver/mobile/app/GoNativeActivity.java
+++ b/internal/driver/mobile/app/GoNativeActivity.java
@@ -27,6 +27,11 @@
 import android.widget.TextView;
 import android.widget.TextView.OnEditorActionListener;
 
+// GoNativeActivity is the java implementation that helps Go map to android via the NDK.
+// If you modify this, you need to regenerate the `dex.go` file with the `gendex` util.
+// They should be located
+// - ./cmd/fyne/internal/mobile/dex.go
+// - ./cmd/fyne/internal/mobile/gendex/
 public class GoNativeActivity extends NativeActivity {
 	private static GoNativeActivity goNativeActivity;
 	private static final int FILE_OPEN_CODE = 1;