diff --git a/include/sys/shm.h b/include/sys/shm.h
index bca6ed62c33990269573f00ed5e4f51b08ebccac..c20f0334861e986ce50a39437e047f704505e4b3 100644
--- a/include/sys/shm.h
+++ b/include/sys/shm.h
@@ -47,6 +47,8 @@ struct shm_info {
 #endif
 };
 
+typedef unsigned long shmatt_t;
+
 void *shmat(int, const void *, int);
 int shmctl(int, int, struct shmid_ds *);
 int shmdt(const void *);