diff --git a/newlib/libc/sys/rtems/include/sys/mman.h b/newlib/libc/sys/rtems/include/sys/mman.h
index 536bfd562..6c757c8ba 100644
--- a/newlib/libc/sys/rtems/include/sys/mman.h
+++ b/newlib/libc/sys/rtems/include/sys/mman.h
@@ -91,6 +91,9 @@
  */
 #define	MAP_NOCORE	 0x00020000 /* dont include these pages in a coredump */
 #define	MAP_PREFAULT_READ 0x00040000 /* prefault mapping for reading */
+#ifdef __LP64__
+#define	MAP_32BIT	 0x00080000 /* map in the low 2GB of address space */
+#endif
 
 /*
  * Request specific alignment (n == log2 of the desired alignment).