diff --git a/src/lib/lwan-pubsub.c b/src/lib/lwan-pubsub.c
index 6761cc0c4..ddd8de1c5 100644
--- a/src/lib/lwan-pubsub.c
+++ b/src/lib/lwan-pubsub.c
@@ -20,6 +20,7 @@
 
 #define _GNU_SOURCE
 #include <errno.h>
+#include <fcntl.h>
 #include <pthread.h>
 #include <stdarg.h>
 #include <stdio.h>