diff --git a/newlib/ChangeLog b/newlib/ChangeLog
index e8d7ee7bb..1aff1c606 100644
--- a/newlib/ChangeLog
+++ b/newlib/ChangeLog
@@ -1,3 +1,8 @@
+2015-12-07  Nick Withers  <nick.withers@anu.edu.au>
+
+	* libc/sys/arm/sys/param.h (NBBY): Define if not already defined.
+	* libc/sys/rtems/include/sys/param.h (NBBY): Define.
+
 2015-12-07  Corinna Vinschen  <corinna@vinschen.de>
 
 	* libc/include/sys/types.h: Move definitions of NBBY and howmany to
diff --git a/newlib/libc/sys/arm/sys/param.h b/newlib/libc/sys/arm/sys/param.h
index b358734a3..5b9464cca 100644
--- a/newlib/libc/sys/arm/sys/param.h
+++ b/newlib/libc/sys/arm/sys/param.h
@@ -6,6 +6,9 @@
 #include <machine/param.h>
 #include <machine/endian.h>
 
+#ifndef NBBY
+# define NBBY 8		/* number of bits in a byte */
+#endif
 #ifndef HZ
 # define HZ (60)
 #endif
diff --git a/newlib/libc/sys/rtems/include/sys/param.h b/newlib/libc/sys/rtems/include/sys/param.h
index f1e598c88..aa0435220 100644
--- a/newlib/libc/sys/rtems/include/sys/param.h
+++ b/newlib/libc/sys/rtems/include/sys/param.h
@@ -109,6 +109,7 @@
 
 #define	NZERO	0		/* default "nice" */
 
+#define	NBBY	8		/* number of bits in a byte */
 #define	NBPW	sizeof(int)	/* number of bytes per word (integer) */
 
 #define	CMASK	022		/* default file mask: S_IWGRP|S_IWOTH */