diff --git a/core/pref.h b/core/pref.h
index c4989e692..198d4b9fe 100644
--- a/core/pref.h
+++ b/core/pref.h
@@ -4,6 +4,8 @@
 
 #ifdef __cplusplus
 extern "C" {
+#else
+#include <stdbool.h>
 #endif
 
 #include "units.h"