diff --git a/clang/runtime/dpct-rt/include/dpl_extras/functional.h.inc b/clang/runtime/dpct-rt/include/dpl_extras/functional.h.inc
index 4e28de1552d5..601f37aebe3f 100644
--- a/clang/runtime/dpct-rt/include/dpl_extras/functional.h.inc
+++ b/clang/runtime/dpct-rt/include/dpl_extras/functional.h.inc
@@ -56,6 +56,12 @@
 
 namespace dpct {
 
+// DPCT_LABEL_BEGIN|null_type|dpct
+// DPCT_DEPENDENCY_EMPTY
+// DPCT_CODE
+struct null_type {};
+// DPCT_LABEL_END
+
 namespace internal {
 
 // DPCT_LABEL_BEGIN|enable_if_execution_policy|dpct::internal
diff --git a/clang/test/dpct/helper_files_ref/include/dpl_extras/functional.h b/clang/test/dpct/helper_files_ref/include/dpl_extras/functional.h
index bdd8cb862799..51afdd8a44eb 100644
--- a/clang/test/dpct/helper_files_ref/include/dpl_extras/functional.h
+++ b/clang/test/dpct/helper_files_ref/include/dpl_extras/functional.h
@@ -22,6 +22,8 @@
 
 namespace dpct {
 
+struct null_type {};
+
 namespace internal {
 
 template <class _ExecPolicy, class _T>