diff --git a/src/windows/save_prompt.c b/src/windows/save_prompt.c
index ef88877004..60d0de0191 100644
--- a/src/windows/save_prompt.c
+++ b/src/windows/save_prompt.c
@@ -120,6 +120,10 @@ void window_save_prompt_open()
 	rct_widget *widgets;
 	uint64 enabled_widgets;
 
+	if (gSavePromptMode >= countof(window_save_prompt_labels)) {
+		log_warning("Invalid save prompt mode %u", gSavePromptMode);
+		return;
+	}
 	prompt_mode = gSavePromptMode;
 	if (prompt_mode == PM_QUIT)
 		prompt_mode = PM_SAVE_BEFORE_QUIT;