diff --git a/include/boost/config/compiler/clang.hpp b/include/boost/config/compiler/clang.hpp
index c030ad71..c2a735f5 100644
--- a/include/boost/config/compiler/clang.hpp
+++ b/include/boost/config/compiler/clang.hpp
@@ -10,6 +10,14 @@
 
 #define BOOST_HAS_PRAGMA_ONCE
 
+// When compiling with clang before __has_extension was defined,
+// even if one writes 'defined(__has_extension) && __has_extension(xxx)',
+// clang reports a compiler error. So the only workaround found is:
+
+#ifndef __has_extension
+#define __has_extension __has_feature
+#endif
+
 #if !__has_feature(cxx_exceptions) && !defined(BOOST_NO_EXCEPTIONS)
 #  define BOOST_NO_EXCEPTIONS
 #endif
diff --git a/include/boost/config/stdlib/dinkumware.hpp b/include/boost/config/stdlib/dinkumware.hpp
index a0ed8702..f31a0cdd 100644
--- a/include/boost/config/stdlib/dinkumware.hpp
+++ b/include/boost/config/stdlib/dinkumware.hpp
@@ -86,7 +86,7 @@
 #  define BOOST_NO_STD_LOCALE
 #endif
 
-// Fix for VC++ 8.0 on up ( I do not have a previous vesion to test )
+// Fix for VC++ 8.0 on up ( I do not have a previous version to test )
 // or clang-cl. If exceptions are off you must manually include the 
 // <exception> header before including the <typeinfo> header. Admittedly 
 // trying to use Boost libraries or the standard C++ libraries without 
diff --git a/test/boost_no_cxx11_user_lit.ipp b/test/boost_no_cxx11_user_lit.ipp
index 375902f7..d1c2054a 100644
--- a/test/boost_no_cxx11_user_lit.ipp
+++ b/test/boost_no_cxx11_user_lit.ipp
@@ -19,7 +19,7 @@ struct my_literal
    constexpr my_literal() : val(0) {}
    constexpr my_literal(int i) : val(i) {}
    constexpr my_literal(const my_literal& a) : val(a.val) {}
-   constexpr bool operator==(const my_literal& a) { return val == a.val; }
+   constexpr bool operator==(const my_literal& a) const { return val == a.val; }
    int val;
 };