diff --git a/tests/Android.bp b/tests/Android.bp
index f1182a7..c751084 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -54,6 +54,9 @@
     sanitize: {
         address: false,
     },
+
+    // Use the bootstrap version of bionic because some tests call private APIs
+    // that aren't exposed by the APEX bionic stubs.
     bootstrap: true,
 
     product_variables: {