diff --git a/src/os_unix.c b/src/os_unix.c
index 80459c9..5eb0936 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -804,9 +804,7 @@
  * completely full.
  */
 
-#if defined(HAVE_AVAILABILITYMACROS_H) \
-    && defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) \
-    && (__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1090)
+#if defined(HAVE_AVAILABILITYMACROS_H)
 # include <AvailabilityMacros.h>
 #endif