diff --git a/BasiliskII/src/MacOSX/configure.in b/BasiliskII/src/MacOSX/configure.in
index ad72cf65..83fae071 100644
--- a/BasiliskII/src/MacOSX/configure.in
+++ b/BasiliskII/src/MacOSX/configure.in
@@ -76,6 +76,12 @@ AC_PROG_CXX
 AC_PROG_MAKE_SET
 AC_PROG_INSTALL
 
+dnl MacOSX (and later?) have a particular header for defining the OS version
+AC_CHECK_HEADER(AvailabilityMacros.h)
+if [[ "x$ac_cv_header_AvailabilityMacros_h" = "xyes" ]]; then
+  DEFINES="$DEFINES -DAVAILABILITYMACROS"
+fi
+
 dnl We use mon if possible.
 MONSRCS=
 if [[ "x$WANT_MON" = "xyes" ]]; then
diff --git a/BasiliskII/src/MacOSX/sysdeps.h b/BasiliskII/src/MacOSX/sysdeps.h
index 682898b7..a37695cc 100644
--- a/BasiliskII/src/MacOSX/sysdeps.h
+++ b/BasiliskII/src/MacOSX/sysdeps.h
@@ -62,7 +62,9 @@
 #endif
 
 
-#include <AvailabilityMacros.h>
+#ifdef AVAILABILITYMACROS
+# include <AvailabilityMacros.h>
+#endif
 
 /* Emulator and host address space are distinct */
 #ifndef REAL_ADDRESSING
@@ -72,9 +74,10 @@
 /* Linear address translation (i.e. just an offset between Emulator & host)  */
 #ifndef DIRECT_ADDRESSING
 # ifdef MAC_OS_X_VERSION_10_2
-/* For some reason, compiling on 10.2 with DIRECT_ADDRESSING enabled */
-/* gives an app that doesn't seem to me able to write to its screen! */
-#  define DIRECT_ADDRESSING 0
+/* For some reason, compiling on 10.2 with DIRECT_ADDRESSING enabled gives an   */
+/* app that never writes to its screen! (i.e. it never calls most of video.cpp) */
+#  define DIRECT_ADDRESSING 1
+//#  define DIRECT_ADDRESSING 0
 # else
 #  define DIRECT_ADDRESSING 1
 # endif