diff --git a/src/shrpx_http3_upstream.cc b/src/shrpx_http3_upstream.cc
index c562e2fc..4dd035af 100644
--- a/src/shrpx_http3_upstream.cc
+++ b/src/shrpx_http3_upstream.cc
@@ -27,6 +27,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <netinet/udp.h>
 
 #include <cstdio>