diff --git a/stk/stk.h b/stk/stk.h
index bea06d7..7d22eb3 100644
--- a/stk/stk.h
+++ b/stk/stk.h
@@ -26,6 +26,7 @@
  */
 #pragma once
 
+#include <stdbool.h>
 #include <stdint.h>
 
 // ---------------------------------------------------------------------------