Index: src/platform/POSIX/OFSubprocess.m
==================================================================
--- src/platform/POSIX/OFSubprocess.m
+++ src/platform/POSIX/OFSubprocess.m
@@ -39,11 +39,14 @@
 #import "OFNotOpenException.h"
 #import "OFOutOfRangeException.h"
 #import "OFReadFailedException.h"
 #import "OFWriteFailedException.h"
 
-#if !defined(HAVE_POSIX_SPAWNP) || !defined(HAVE_SPAWN_H)
+#ifdef OF_MACOS
+# include <crt_externs.h>
+# define environ (*_NSGetEnviron())
+#elif !defined(HAVE_POSIX_SPAWNP) || !defined(HAVE_SPAWN_H)
 extern char **environ;
 #endif
 
 @interface OFSubprocess ()
 - (void)of_getArgv: (char ***)argv