diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index 4d051a246ab..074ae0f40de 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -135,7 +135,8 @@ var (
 // to start new os thread.
 func tstart_stdcall(newm *m)
 
-func ctrlhandler(_type uint32)
+// Called by OS using stdcall ABI.
+func ctrlhandler()
 
 type mOS struct {
 	waitsema uintptr // semaphore for parking on locks
diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s
index 39ebe1bdf9b..2aea8eaff7e 100644
--- a/src/runtime/sys_windows_amd64.s
+++ b/src/runtime/sys_windows_amd64.s
@@ -211,7 +211,7 @@ TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
 	JMP	sigtramp<>(SB)
 
 TEXT runtime·ctrlhandler(SB),NOSPLIT|NOFRAME,$8
-	MOVQ	CX, _type+16(SP)		// spill
+	MOVQ	CX, 16(SP)		// spill
 	MOVQ	$runtime·ctrlhandler1(SB), CX
 	MOVQ	CX, 0(SP)
 	CALL	runtime·externalthreadhandler(SB)