diff --git a/aidl_unittest.cpp b/aidl_unittest.cpp
index c1a2137..e3a761b 100644
--- a/aidl_unittest.cpp
+++ b/aidl_unittest.cpp
@@ -1606,6 +1606,19 @@
   EXPECT_THAT(GetCapturedStderr(), HasSubstr("Interfaces should be at the root scope"));
 }
 
+TEST_F(AidlTest, RejectUnstructuredParcelableAsNestedTypes) {
+  const string input_path = "p/IFoo.aidl";
+  const string input =
+      "package p;\n"
+      "interface IFoo {\n"
+      "  parcelable Bar cpp_header \"Bar.h\";\n"
+      "}";
+  CaptureStderr();
+  EXPECT_EQ(nullptr, Parse(input_path, input, typenames_, Options::Language::CPP));
+  EXPECT_THAT(GetCapturedStderr(),
+              HasSubstr("Unstructured parcelables should be at the root scope"));
+}
+
 TEST_F(AidlTest, HandleSyntaxErrorsInNestedDecl) {
   const string input_path = "p/IFoo.aidl";
   const string input =