diff --git a/sys/arm/arm/locore-v6.S b/sys/arm/arm/locore-v6.S
index d90dd6069e1c..1e2954536fa3 100644
--- a/sys/arm/arm/locore-v6.S
+++ b/sys/arm/arm/locore-v6.S
@@ -461,7 +461,7 @@ ENTRY_NP(cpu_halt)
 	teq	r4, #0
 	movne	pc, r4
 1:	
-	wfi
+	WFI
 	b	1b
 
 	/*
diff --git a/sys/arm/include/asm.h b/sys/arm/include/asm.h
index 9122e6ea3a30..a18286307f00 100644
--- a/sys/arm/include/asm.h
+++ b/sys/arm/include/asm.h
@@ -227,14 +227,17 @@
 #define ISB	isb
 #define DSB	dsb
 #define DMB	dmb
+#define WFI	wfi
 #elif __ARM_ARCH == 6
 #define ISB	mcr CP15_CP15ISB
 #define DSB	mcr CP15_CP15DSB
 #define DMB	mcr CP15_CP15DMB
+#define WFI	mcr CP15_CP15WFI
 #else
 #define ISB	mcr CP15_CP15ISB
 #define DSB	mcr CP15_CP15DSB	/* DSB and DMB are the */
 #define DMB	mcr CP15_CP15DSB	/* same prior to v6.*/
+/* No form of WFI available on v4, define nothing to get an error on use. */
 #endif
 
 #endif /* !_MACHINE_ASM_H_ */
diff --git a/sys/arm/include/sysreg.h b/sys/arm/include/sysreg.h
index b1c7fd373b59..ad29703fa885 100644
--- a/sys/arm/include/sysreg.h
+++ b/sys/arm/include/sysreg.h
@@ -166,6 +166,7 @@
 /* Only ARMv6: */
 #define	CP15_CP15DSB		p15, 0, r0, c7, c10, 4 /* DSB */
 #define	CP15_CP15DMB		p15, 0, r0, c7, c10, 5 /* DMB */
+#define	CP15_CP15WFI		p15, 0, r0, c7, c0,  4 /* WFI */
 #endif
 
 #if __ARM_ARCH >= 7