diff --git a/api/StubLibraries.bp b/api/StubLibraries.bp
index c59a833..2f84df7 100644
--- a/api/StubLibraries.bp
+++ b/api/StubLibraries.bp
@@ -33,7 +33,7 @@
         "android-non-updatable-stubs-defaults",
         "module-classpath-stubs-defaults",
     ],
-    args: metalava_framework_docs_args,
+    args: metalava_framework_docs_args + "--error UnflaggedApi ",
     check_api: {
         current: {
             api_file: ":non-updatable-current.txt",