diff --git a/sys/sparc64/include/pcpu.h b/sys/sparc64/include/pcpu.h
index bf3d4afbdb8f..c54c45b2443f 100644
--- a/sys/sparc64/include/pcpu.h
+++ b/sys/sparc64/include/pcpu.h
@@ -71,8 +71,8 @@ extern void *dpcpu0;
 struct pcb;
 struct pcpu;
 
-struct pcb *curpcb __asm__(__XSTRING(PCB_REG));
-struct pcpu *pcpup __asm__(__XSTRING(PCPU_REG));
+register struct pcb *curpcb __asm__(__XSTRING(PCB_REG));
+register struct pcpu *pcpup __asm__(__XSTRING(PCPU_REG));
 
 #define	get_pcpu()		(pcpup)
 #define	PCPU_GET(member)	(pcpup->pc_ ## member)