diff --git a/newlib/libc/sys/rtems/include/sys/mman.h b/newlib/libc/sys/rtems/include/sys/mman.h
index 7a9b49429..99c1eb8b3 100644
--- a/newlib/libc/sys/rtems/include/sys/mman.h
+++ b/newlib/libc/sys/rtems/include/sys/mman.h
@@ -190,6 +190,7 @@
  * shmflags for shm_open2()
  */
 #define	SHM_ALLOW_SEALING		0x00000001
+#define	SHM_GROW_ON_WRITE		0x00000002
 
 /*
  * Flags for memfd_create().