--- nono/vm/interrupt.cpp	2026/04/29 17:05:37	1.1.1.12
+++ nono/vm/interrupt.cpp	2026/04/29 17:05:46	1.1.1.13
@@ -615,8 +615,7 @@ Virt68kInterrupt::Init()
 void
 Virt68kInterrupt::IncMonitorHeight()
 {
-	auto size = monitor->GetSize();
-	monitor->SetSize(size.width, size.height + 1);
+	monitor->AddHeight(1);
 }
 
 // 割り込みアクノリッジに応答する