diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index b6ff20c5..25bc294f 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -2,9 +2,9 @@ set(cilk_header_files
   cilk/cilk.h
   cilk/cilk_api.h
   cilk/cilk_stub.h
-  cilk/holder.h
-  cilk/opadd_reducer.h
-  cilk/ostream_reducer.h
+  cilk/holder
+  cilk/opadd_reducer
+  cilk/ostream_reducer
   cilk/reducer)
 
 set(output_dir ${CHEETAH_OUTPUT_DIR}/include)
diff --git a/include/cilk/cilk.h b/include/cilk/cilk.h
index 7014987a..c5fcde2f 100644
--- a/include/cilk/cilk.h
+++ b/include/cilk/cilk.h
@@ -1,6 +1,8 @@
 #ifndef _CILK_H
 #define  _CILK_H
 
+#if __cilk < 301
+
 #define cilk_spawn _Cilk_spawn
 #define cilk_sync  _Cilk_sync
 #define cilk_for   _Cilk_for
@@ -8,4 +10,6 @@
 
 #define cilk_reducer _Hyperobject
 
+#endif
+
 #endif /* _CILK_H */
diff --git a/include/cilk/holder.h b/include/cilk/holder
similarity index 79%
rename from include/cilk/holder.h
rename to include/cilk/holder
index 2f36e770..1a8a743d 100644
--- a/include/cilk/holder.h
+++ b/include/cilk/holder
@@ -1,8 +1,6 @@
 #ifndef _HOLDER_H
 #define _HOLDER_H
 
-#ifdef __cplusplus
-
 #include <type_traits>
 
 namespace cilk {
@@ -16,10 +14,8 @@ template <typename A> static void reduce(void *left, void *right) {
 }
 
 template <typename A>
-using holder = A _Hyperobject(init<A>, reduce<A>);
+using holder = A cilk_reducer(init<A>, reduce<A>);
 
 } // namespace cilk
 
-#endif // __cplusplus
-
 #endif // _HOLDER_H
diff --git a/include/cilk/opadd_reducer.h b/include/cilk/opadd_reducer
similarity index 75%
rename from include/cilk/opadd_reducer.h
rename to include/cilk/opadd_reducer
index be7c2696..b8118ff2 100644
--- a/include/cilk/opadd_reducer.h
+++ b/include/cilk/opadd_reducer
@@ -1,8 +1,6 @@
 #ifndef _OPADD_REDUCER_H
 #define _OPADD_REDUCER_H
 
-#ifdef __cplusplus
-
 namespace cilk {
 
 template <typename T> static void zero(void *v) {
@@ -13,10 +11,8 @@ template <typename T> static void plus(void *l, void *r) {
     *static_cast<T *>(l) += *static_cast<T *>(r);
 }
 
-template <typename T> using opadd_reducer = T _Hyperobject(zero<T>, plus<T>);
+template <typename T> using opadd_reducer = T cilk_reducer(zero<T>, plus<T>);
 
 } // namespace cilk
 
-#endif // #ifdef __cplusplus
-
 #endif // _OPADD_REDUCER_H
diff --git a/include/cilk/ostream_reducer.h b/include/cilk/ostream_reducer
similarity index 91%
rename from include/cilk/ostream_reducer.h
rename to include/cilk/ostream_reducer
index 88113132..07449c17 100644
--- a/include/cilk/ostream_reducer.h
+++ b/include/cilk/ostream_reducer
@@ -1,8 +1,6 @@
 #ifndef _OSTREAM_REDUCER_H
 #define _OSTREAM_REDUCER_H
 
-#ifdef __cplusplus
-
 #include <ostream>
 #include <sstream>
 
@@ -64,11 +62,9 @@ class ostream_view : public std::basic_ostream<Char, Traits>
 
 template<typename Char, typename Traits = std::char_traits<Char>>
   using ostream_reducer = ostream_view<Char, Traits>
-    _Hyperobject(&ostream_view<Char, std::char_traits<Char>>::identity,
-                 &ostream_view<Char, std::char_traits<Char>>::reduce);
+    cilk_reducer(&ostream_view<Char, Traits>::identity,
+                 &ostream_view<Char, Traits>::reduce);
 
 } // namespace cilk
 
-#endif // __cplusplus
-
 #endif // _OSTREAM_REDUCER_H