diff --git a/src/misc/pv/sharedPtr.h b/src/misc/pv/sharedPtr.h
index 3fba962..5bc968a 100644
--- a/src/misc/pv/sharedPtr.h
+++ b/src/misc/pv/sharedPtr.h
@@ -62,9 +62,9 @@
 #if defined(SHARED_FROM_MANUAL)
 // define SHARED_FROM_MANUAL if from some reason it is desirable to manually select
 // which shared_ptr implementation to use
-#elif __cplusplus>=201103L || (defined(_MSC_VER) && (_MSC_VER>=1600)) || (__clang__ && __APPLE__)
-// c++11 or MSVC 2010
-// clang on linux has tr1/memory, clang on OSX doesn't
+#elif __cplusplus>=201103L || (defined(_MSC_VER) && (_MSC_VER>=1600)) || defined(_LIBCPP_VERSION)
+// MSVC has been bad about incrementing __cplusplus, even when new features are added.  shared_ptr from MSVC 2010
+// the llvm libc++ doesn't bother with tr1, and puts shared_ptr in std:: even with -std=c++98
 #  define SHARED_FROM_STD
 
 #elif defined(__GNUC__) && __GNUC__>=4 && !defined(vxWorks)