diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s
index b0e1864602..3a96c2bf91 100644
--- a/src/runtime/sys_plan9_amd64.s
+++ b/src/runtime/sys_plan9_amd64.s
@@ -149,7 +149,7 @@ TEXT runtime·tstart_plan9(SB),NOSPLIT,$0
 
 	// Initialize procid from TOS struct.
 	MOVQ	_tos(SB), AX
-	MOVQ	64(AX), AX
+	MOVL	64(AX), AX
 	MOVQ	AX, m_procid(CX)	// save pid as m->procid
 
 	// Finally, initialize g.