--- ./lib/system/certs.c.old	2017-04-14 10:36:27.000000000 -0700
+++ ./lib/system/certs.c	2017-04-14 10:37:10.000000000 -0700
@@ -47,8 +47,15 @@
 #ifdef __APPLE__
 # include <CoreFoundation/CoreFoundation.h>
 # include <Security/Security.h>
+#ifndef __MAC_OS_X_VERSION_MIN_REQUIRED
+#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
 # include <Availability.h>
+#else
+# include <AvailabilityMacros.h>
+#endif
 #endif
+#endif
+
 
 /* System specific function wrappers for certificate stores.
  */