diff --git a/src/common/dns_utils.h b/src/common/dns_utils.h
index 61e1358ca..f19584516 100644
--- a/src/common/dns_utils.h
+++ b/src/common/dns_utils.h
@@ -29,6 +29,7 @@
 
 #include <vector>
 #include <string>
+#include <functional>
 
 namespace tools
 {