diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index b29486462053..952a70b87abf 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -338,19 +338,16 @@ ENTRY(savectx)
 
 	movl	$MSR_FSBASE,%ecx
 	rdmsr
-	shlq	$32,%rdx
-	leaq	(%rax,%rdx),%rax
-	movq	%rax,PCB_FSBASE(%rdi)
+	movl	%eax,PCB_FSBASE(%rdi)
+	movl	%edx,PCB_FSBASE+4(%rdi)
 	movl	$MSR_GSBASE,%ecx
 	rdmsr
-	shlq	$32,%rdx
-	leaq	(%rax,%rdx),%rax
-	movq	%rax,PCB_GSBASE(%rdi)
+	movl	%eax,PCB_GSBASE(%rdi)
+	movl	%edx,PCB_GSBASE+4(%rdi)
 	movl	$MSR_KGSBASE,%ecx
 	rdmsr
-	shlq	$32,%rdx
-	leaq	(%rax,%rdx),%rax
-	movq	%rax,PCB_KGSBASE(%rdi)
+	movl	%eax,PCB_KGSBASE(%rdi)
+	movl	%edx,PCB_KGSBASE+4(%rdi)
 
 	sgdt	PCB_GDT(%rdi)
 	sidt	PCB_IDT(%rdi)