diff --git a/test_tui.c b/test_tui.c
index 9a07d65..23211e9 100644
--- a/test_tui.c
+++ b/test_tui.c
@@ -4,6 +4,7 @@
 #include <assert.h>
 #include "engine.h"
 #include <stdatomic.h>
+#include <stdbool.h>
 #include "tui.h"
 
 // Mode definitions (mirrored from tui.c)