diff --git a/polyp/module-protocol-stub.c b/polyp/module-protocol-stub.c
index 0b91c68cd..37a17c86d 100644
--- a/polyp/module-protocol-stub.c
+++ b/polyp/module-protocol-stub.c
@@ -29,6 +29,9 @@
 #include <assert.h>
 #include <unistd.h>
 
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
 #ifdef HAVE_ARPA_INET_H
 #include <arpa/inet.h>
 #endif