diff --git a/Misc/NEWS.d/next/Build/2021-01-04-05-07-30.bpo-42692.OO11SN.rst b/Misc/NEWS.d/next/Build/2021-01-04-05-07-30.bpo-42692.OO11SN.rst
new file mode 100644
index 00000000000000..91582b945b803f
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-01-04-05-07-30.bpo-42692.OO11SN.rst
@@ -0,0 +1 @@
+Fix __builtin_available check on older compilers. Patch by Joshua Root.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index d2ce8339e61f06..5e33502721c192 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -56,7 +56,13 @@
  */
 #if defined(__APPLE__)
 
-#if defined(__has_builtin) && __has_builtin(__builtin_available)
+#if defined(__has_builtin)
+#if __has_builtin(__builtin_available)
+#define HAVE_BUILTIN_AVAILABLE 1
+#endif
+#endif
+
+#ifdef HAVE_BUILTIN_AVAILABLE
 #  define HAVE_FSTATAT_RUNTIME __builtin_available(macOS 10.10, iOS 8.0, *)
 #  define HAVE_FACCESSAT_RUNTIME __builtin_available(macOS 10.10, iOS 8.0, *)
 #  define HAVE_FCHMODAT_RUNTIME __builtin_available(macOS 10.10, iOS 8.0, *)