diff --git a/src/auto/configure b/src/auto/configure
index 07f794e..9f43e8d 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -4223,7 +4223,7 @@
     OS_EXTRA_OBJ="objects/os_macosx.o objects/os_mac_conv.o"
         CPPFLAGS="$CPPFLAGS -DMACOS_X_UNIX -no-cpp-precomp"
 
-                # On IRIX 5.3, sys/types and inttypes.h are conflicting.
+            # On IRIX 5.3, sys/types and inttypes.h are conflicting.
 for ac_header in sys/types.h sys/stat.h stdlib.h string.h memory.h strings.h \
 		  inttypes.h stdint.h unistd.h
 do :
@@ -4241,7 +4241,16 @@
 done
 
 
-ac_fn_c_check_header_mongrel "$LINENO" "Carbon/Carbon.h" "ac_cv_header_Carbon_Carbon_h" "$ac_includes_default"
+ac_fn_c_check_header_mongrel "$LINENO" "AvailabilityMacros.h" "ac_cv_header_AvailabilityMacros_h" "$ac_includes_default"
+if test "x$ac_cv_header_AvailabilityMacros_h" = x""yes; then :
+
+$as_echo "#define HAVE_AVAILABILITYMACROS_H 1" >>confdefs.h
+
+fi
+
+
+
+                ac_fn_c_check_header_mongrel "$LINENO" "Carbon/Carbon.h" "ac_cv_header_Carbon_Carbon_h" "$ac_includes_default"
 if test "x$ac_cv_header_Carbon_Carbon_h" = x""yes; then :
   CARBON=yes
 fi
diff --git a/src/config.h.in b/src/config.h.in
index 422fd1f..a4e216b 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -442,3 +442,6 @@
 
 /* Define if you want Cygwin to use the WIN32 clipboard, not compatible with X11*/
 #undef FEAT_CYGWIN_WIN32_CLIPBOARD
+
+/* Define if we have AvailabilityMacros.h on Mac OS X */
+#undef HAVE_AVAILABILITYMACROS_H
diff --git a/src/configure.in b/src/configure.in
index 11e1d63..73470fc 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -206,6 +206,10 @@
     dnl TODO: use -arch i386 on Intel machines
     CPPFLAGS="$CPPFLAGS -DMACOS_X_UNIX -no-cpp-precomp"
 
+    dnl Mac OS X 10.9+ no longer include AvailabilityMacros.h in Carbon
+    dnl so we need to include it to have access to version macros.
+    AC_CHECK_HEADER(AvailabilityMacros.h, [AC_DEFINE(HAVE_AVAILABILITYMACROS_H, 1, [ Define if we have AvailabilityMacros.h on Mac OS X ])])
+
     dnl If Carbon is found, assume we don't want X11
     dnl unless it was specifically asked for (--with-x)
     dnl or Motif, Athena or GTK GUI is used.
diff --git a/src/os_mac.h b/src/os_mac.h
index 78b79c2..c13a301 100644
--- a/src/os_mac.h
+++ b/src/os_mac.h
@@ -16,6 +16,11 @@
 # define OPAQUE_TOOLBOX_STRUCTS 0
 #endif
 
+/* Include MAC_OS_X_VERSION_* macros */
+#ifdef HAVE_AVAILABILITYMACROS_H
+# include <AvailabilityMacros.h>
+#endif
+
 /*
  * Macintosh machine-dependent things.
  *
@@ -263,7 +268,7 @@
 #endif
 
 /* Some "prep work" definition to be able to compile the MacOS X
- * version with os_unix.x instead of os_mac.c. Based on the result
+ * version with os_unix.c instead of os_mac.c. Based on the result
  * of ./configure for console MacOS X.
  */
 
diff --git a/src/version.c b/src/version.c
index c221725..184aee7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    55,
+/**/
     54,
 /**/
     53,