diff --git a/headers/posix/spawn.h b/headers/posix/spawn.h
index 4726b53a0e..c3a0b1412d 100644
--- a/headers/posix/spawn.h
+++ b/headers/posix/spawn.h
@@ -23,6 +23,7 @@
 #endif	/* 0 */
 #define POSIX_SPAWN_SETSIGDEF		0x10
 #define POSIX_SPAWN_SETSIGMASK		0x20
+#define POSIX_SPAWN_SETSID			0x40
 
 
 typedef struct _posix_spawnattr	*posix_spawnattr_t;
diff --git a/src/system/libroot/posix/spawn.cpp b/src/system/libroot/posix/spawn.cpp
index 5bbd454f50..473a3b067d 100644
--- a/src/system/libroot/posix/spawn.cpp
+++ b/src/system/libroot/posix/spawn.cpp
@@ -361,6 +361,11 @@ process_spawnattr(const posix_spawnattr_t *_attr)
 			return errno;
 	}
 
+	if ((attr->flags & POSIX_SPAWN_SETSID) != 0) {
+		if (setsid() != 0)
+			return errno;
+	}
+
 	if ((attr->flags & POSIX_SPAWN_SETPGROUP) != 0) {
 		if (setpgid(0, attr->pgroup) != 0)
 			return errno;