diff --git a/mach/i86/libem/csb4.s b/mach/i86/libem/csb4.s
index bdb812f1c..8ac3f0566 100644
--- a/mach/i86/libem/csb4.s
+++ b/mach/i86/libem/csb4.s
@@ -16,7 +16,7 @@
 	jne     1b
 	cmp	dx,2(bx)
 	jne     1b
-	pop	bx
+	pop	cx
 	mov	bx,4(bx)
 2:
 	test    bx,bx