diff --git a/src/include/lwip/dns.h b/src/include/lwip/dns.h
index 1453d723..09134154 100644
--- a/src/include/lwip/dns.h
+++ b/src/include/lwip/dns.h
@@ -44,6 +44,7 @@
 #if LWIP_DNS
 
 #include "lwip/ip_addr.h"
+#include "lwip/err.h"
 
 #ifdef __cplusplus
 extern "C" {