diff --git a/sys/arm/include/bus.h b/sys/arm/include/bus.h
index 4080c337135..cabf1f7c588 100644
--- a/sys/arm/include/bus.h
+++ b/sys/arm/include/bus.h
@@ -721,6 +721,8 @@ bs_c_8_proto(f);
 #define BUS_SPACE_MAXSIZE_32BIT	0xFFFFFFFF
 #define BUS_SPACE_MAXSIZE 	0xFFFFFFFF
 
+#define BUS_SPACE_UNRESTRICTED	(~0)
+
 #include <machine/bus_dma.h>
 
 #endif /* _MACHINE_BUS_H_ */
diff --git a/sys/mips/include/bus.h b/sys/mips/include/bus.h
index ccaeb34b186..2ab347b4b9c 100644
--- a/sys/mips/include/bus.h
+++ b/sys/mips/include/bus.h
@@ -713,6 +713,8 @@ void	__bs_c(f,_bs_c_8) (void *t, bus_space_handle_t bsh1,	\
 #define BUS_SPACE_MAXSIZE_32BIT	0xFFFFFFFF
 #define BUS_SPACE_MAXSIZE 	0xFFFFFFFF
 
+#define BUS_SPACE_UNRESTRICTED	(~0)
+
 /* 
  * declare generic bus space, it suits all needs in 
  */