--- mnt.cc	2018-04-18 14:11:19.000000000 +0200
+++ mnt.cc	2018-04-21 13:07:43.814692651 +0200
@@ -47,6 +47,11 @@
 #include "subproc.h"
 #include "util.h"
 
+#if !defined(ST_RELATIME)
+/* In musl libc this is not (yet?) defined */
+#define ST_RELATIME 4096
+#endif
+
 namespace mnt {
 
 #if !defined(MS_LAZYTIME)
