diff --git a/cudax/examples/stf/void_data_interface.cu b/cudax/examples/stf/void_data_interface.cu
index 0340b16bf4a..bf429f23dfe 100644
--- a/cudax/examples/stf/void_data_interface.cu
+++ b/cudax/examples/stf/void_data_interface.cu
@@ -49,5 +49,9 @@ int main()
     return cuda_kernel_desc{dummy_kernel, 16, 128, 0};
   };
 
+  EXPECT(token.is_void_interface());
+  EXPECT(token2.is_void_interface());
+  EXPECT(token3.is_void_interface());
+
   ctx.finalize();
 }
diff --git a/cudax/test/stf/cpp/task_get_stream.cu b/cudax/test/stf/cpp/task_get_stream.cu
index 89fa74e7490..2d6509e5a73 100644
--- a/cudax/test/stf/cpp/task_get_stream.cu
+++ b/cudax/test/stf/cpp/task_get_stream.cu
@@ -24,7 +24,8 @@ void test_stream()
   context ctx;
 
   auto token = ctx.token();
-  auto t     = ctx.task(token.write());
+  EXPECT(token.is_void_interface());
+  auto t = ctx.task(token.write());
   t.start();
   cudaStream_t s = t.get_stream();
   EXPECT(s != nullptr);