https://bugs.gentoo.org/890987
--- a/src/custom.cc
+++ b/src/custom.cc
@@ -44,6 +44,7 @@
 #include "init_consts.h"
 #include "print_inode_to.h"
 #include <sys/time.h>
+#include <cassert>
 #include <cstring>
 #include <ctime>