diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index 684d8c3eb780..6c1cd82ee84f 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -43,6 +43,8 @@
 #include <sys/tslog.h>
 #include <sys/_mutex.h>
 #include <sys/_sx.h>
+#else
+#include <stdbool.h>
 #endif
 
 /*