diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S
index 2f2897613d16..05e5f988f2b6 100644
--- a/sys/amd64/amd64/support.S
+++ b/sys/amd64/amd64/support.S
@@ -1155,7 +1155,6 @@ ENTRY(suword16_nosmap)
 
 	movw	%si,(%rdi)
 	xorl	%eax,%eax
-	movq	PCPU(CURPCB),%rcx		/* restore trashed register */
 	movq	%rax,PCB_ONFAULT(%rcx)
 	POP_FRAME_POINTER
 	ret
@@ -1174,7 +1173,6 @@ ENTRY(suword16_smap)
 	movw	%si,(%rdi)
 	clac
 	xorl	%eax,%eax
-	movq	PCPU(CURPCB),%rcx		/* restore trashed register */
 	movq	%rax,PCB_ONFAULT(%rcx)
 	POP_FRAME_POINTER
 	ret
@@ -1192,7 +1190,6 @@ ENTRY(subyte_nosmap)
 	movl	%esi,%eax
 	movb	%al,(%rdi)
 	xorl	%eax,%eax
-	movq	PCPU(CURPCB),%rcx		/* restore trashed register */
 	movq	%rax,PCB_ONFAULT(%rcx)
 	POP_FRAME_POINTER
 	ret
@@ -1212,7 +1209,6 @@ ENTRY(subyte_smap)
 	movb	%al,(%rdi)
 	clac
 	xorl	%eax,%eax
-	movq	PCPU(CURPCB),%rcx		/* restore trashed register */
 	movq	%rax,PCB_ONFAULT(%rcx)
 	POP_FRAME_POINTER
 	ret