diff --git a/example/multi_thread/openmp/get_started.cpp b/example/multi_thread/openmp/get_started.cpp
index 4e3030539..b483119a8 100644
--- a/example/multi_thread/openmp/get_started.cpp
+++ b/example/multi_thread/openmp/get_started.cpp
@@ -75,7 +75,8 @@ namespace {
    double partial(
       CppAD::ADFun<double>& f, size_t j, const d_vector& x
    )
-   {  //
+   {  // f
+      // This will cause an assert if USE_DEFAULT_ADFUN_CONSTRUCTOR is 0.
       f.capacity_order(0);
       //
       size_t nx = x.size();