diff --git a/Misc/NEWS.d/next/macOS/2020-06-24-13-51-57.bpo-41100.mcHdc5.rst b/Misc/NEWS.d/next/macOS/2020-06-24-13-51-57.bpo-41100.mcHdc5.rst
new file mode 100644
index 00000000000000..ded66b567a92db
--- /dev/null
+++ b/Misc/NEWS.d/next/macOS/2020-06-24-13-51-57.bpo-41100.mcHdc5.rst
@@ -0,0 +1 @@
+Support macOS 11 when building.
diff --git a/configure b/configure
index e39c16eee2b903..6810acab3538de 100755
--- a/configure
+++ b/configure
@@ -3375,7 +3375,7 @@ $as_echo "#define _BSD_SOURCE 1" >>confdefs.h
   # has no effect, don't bother defining them
   Darwin/[6789].*)
     define_xopen_source=no;;
-  Darwin/1[0-9].*)
+  Darwin/[12][0-9].*)
     define_xopen_source=no;;
   # On AIX 4 and 5.1, mbstate_t is defined only when _XOPEN_SOURCE == 500 but
   # used in wcsnrtombs() and mbsnrtowcs() even if _XOPEN_SOURCE is not defined
diff --git a/configure.ac b/configure.ac
index cf280506bd011f..8122e65b438d00 100644
--- a/configure.ac
+++ b/configure.ac
@@ -495,7 +495,7 @@ case $ac_sys_system/$ac_sys_release in
   # has no effect, don't bother defining them
   Darwin/@<:@6789@:>@.*)
     define_xopen_source=no;;
-  Darwin/1@<:@0-9@:>@.*)
+  Darwin/@<:@[12]@:>@@<:@0-9@:>@.*)
     define_xopen_source=no;;
   # On AIX 4 and 5.1, mbstate_t is defined only when _XOPEN_SOURCE == 500 but
   # used in wcsnrtombs() and mbsnrtowcs() even if _XOPEN_SOURCE is not defined