diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index f34b0cc..03f0eca 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -249,6 +249,12 @@ store_seg:
 1:	movl	%ds,PCB_DS(%r8)
 	movl	%es,PCB_ES(%r8)
 	movl	%fs,PCB_FS(%r8)
+	movq	%rdx,%r11
+	movl	$MSR_FSBASE,%ecx
+	rdmsr
+	shlq	$32,%rdx
+	leaq	(%rax,%rdx),%r9
+	movq	%r11,%rdx
 	jmp	done_store_seg
 2:	movq	PCB_GS32P(%r8),%rax
 	movq	(%rax),%rax