diff --git a/socket-enhancer.c b/socket-enhancer.c
index 49be28d..7791745 100644
--- a/socket-enhancer.c
+++ b/socket-enhancer.c
@@ -1,5 +1,6 @@
 #define _GNU_SOURCE
 #include <stdio.h>
+#include <errno.h>
 #include <stdlib.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>