diff --git a/include/unistd.h b/include/unistd.h
index 53efe498b681..6a0d25e4d2ae 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -107,7 +107,7 @@ typedef	__useconds_t	useconds_t;
 #define	_POSIX_READER_WRITER_LOCKS	200112L
 #define	_POSIX_REGEXP			1
 #define	_POSIX_SHELL			1
-#define	_POSIX_SPAWN			-1
+#define	_POSIX_SPAWN			200112L
 #define	_POSIX_SPIN_LOCKS		200112L
 #define	_POSIX_THREAD_ATTR_STACKADDR	200112L
 #define	_POSIX_THREAD_ATTR_STACKSIZE	200112L