diff --git a/changes/bug20935 b/changes/bug20935
new file mode 100644
index 000000000..78068c7c0
--- /dev/null
+++ b/changes/bug20935
@@ -0,0 +1,3 @@
+  o Minor bugfixes (portability):
+    - Use the correct spelling of MAC_OS_X_VERSION_10_12 on configure.ac
+      Fixes bug 20935; bugfix on 0.2.9.6-rc.
diff --git a/configure.ac b/configure.ac
index df68ffa8f..699eafc51 100644
--- a/configure.ac
+++ b/configure.ac
@@ -430,11 +430,11 @@ AC_MSG_CHECKING([for a pre-Sierra OSX build target])
 AC_TRY_COMPILE([
 #ifdef __APPLE__
 #  include <AvailabilityMacros.h>
-#  ifndef MAC_OS_VERSION_10_12
-#    define MAC_OS_VERSION_10_12 101200
+#  ifndef MAC_OS_X_VERSION_10_12
+#    define MAC_OS_X_VERSION_10_12 101200
 #  endif
 #  if defined(MAC_OS_X_VERSION_MIN_REQUIRED)
-#    if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_VERSION_10_12
+#    if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_12
 #      error "Running on Mac OSX 10.11 or earlier"
 #    endif
 #  endif