diff --git a/sys/amd64/linux/linux_sysvec.c b/sys/amd64/linux/linux_sysvec.c
--- a/sys/amd64/linux/linux_sysvec.c
+++ b/sys/amd64/linux/linux_sysvec.c
@@ -169,6 +169,8 @@
 
 	/* Restore r10 earlier to avoid doing this multiply times. */
 	frame->tf_r10 = frame->tf_rcx;
+	/* Restore %rcx for machine context. */
+	frame->tf_rcx = frame->tf_rip;
 
 	td->td_retval[0] = 0;
 	return (0);