diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index ac527f2..685e336 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -644,7 +644,7 @@
     memcpy(&prev[prev_len++], delay, sizeof(packet));
 }
 
-int send_delayed()
+int send_delayed(void)
 {
     uint8_t offset;
     int ret;