--- dnsdist-1.6.0/lock.hh	2021-05-17 23:30:36.284654809 +0200
+++ dnsdist-1.6.0/lock.hh	2021-05-17 23:29:56.689998795 +0200
@@ -21,6 +21,7 @@
  */
 #pragma once
 #include <shared_mutex>
+#include <mutex>
 
 class ReadWriteLock
 {