diff --git a/include/boost/config/platform/bsd.hpp b/include/boost/config/platform/bsd.hpp
index 12160486..ee861bee 100644
--- a/include/boost/config/platform/bsd.hpp
+++ b/include/boost/config/platform/bsd.hpp
@@ -29,8 +29,11 @@
 #endif
 
 //
-// no wide character support:
+// No wide character support in the BSD header files:
 //
 #define BOOST_NO_CWCHAR
 
-
+//
+// The BSD <ctype.h> has macros only, no functions:
+//
+#define BOOST_NO_CTYPE_FUNCTIONS
diff --git a/include/boost/config/platform/macos.hpp b/include/boost/config/platform/macos.hpp
index 0f8a160f..010352a7 100644
--- a/include/boost/config/platform/macos.hpp
+++ b/include/boost/config/platform/macos.hpp
@@ -9,18 +9,15 @@
 
 #define BOOST_PLATFORM "Mac OS"
 
-// if __MACH__, we're using the BSD standard C library, not the MSL
+// If __MACH__, we're using the BSD standard C library, not the MSL:
 #if defined(__MACH__)
-#  define BOOST_HAS_UNISTD_H
+#  define BOOST_NO_CTYPE_FUNCTIONS
 #  define BOOST_NO_CWCHAR
 #  define BOOST_NO_STDC_NAMESPACE
+#  ifndef BOOST_HAS_UNISTD_H
+#    define BOOST_HAS_UNISTD_H
+#  endif
 #  ifndef BOOST_HAS_STDINT_H
 #     define BOOST_HAS_STDINT_H
 #  endif
 #endif
-
-
-
-
-
-