diff --git a/cmake/FindCompilerCheck.cmake b/cmake/FindCompilerCheck.cmake
index 7b0af8ba..bdc9daba 100644
--- a/cmake/FindCompilerCheck.cmake
+++ b/cmake/FindCompilerCheck.cmake
@@ -47,7 +47,7 @@ elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
 
  # does not always work ... To be fixed when clang 3.4 officially released and on OS X.
  if(NOT compiler_version VERSION_LESS "3.4")
-  #set (compiler_is_c14 ON)
+  set (compiler_is_c14 ON)
  endif()
 
 elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Intel")
diff --git a/triqs/clef/clef.c14.hpp b/triqs/clef/clef.c14.hpp
index 55755a4d..21e51589 100644
--- a/triqs/clef/clef.c14.hpp
+++ b/triqs/clef/clef.c14.hpp
@@ -380,7 +380,8 @@ namespace triqs { namespace clef {
  template<int ... N> ph_list<N...> var( placeholder<N> ...) { return {};}
 
  template<typename Expr, int ... N> 
-  decltype(auto) operator >> (ph_list<N...>, Expr const & ex)  { return  make_function(ex, placeholder<N>()...);}
+  auto operator >> (ph_list<N...> &&, Expr const & ex) ->decltype(make_function(ex, placeholder<N>()...)) { return  make_function(ex, placeholder<N>()...);}
+  // add trailing as a workaround around a clang bug here on xcode 5.1.1 (?)
 
  /* --------------------------------------------------------------------------------------------------
   *  make_function