diff --git a/mongoose.c b/mongoose.c
index 97cc733121eac2116e5487a16f246d65b6565ffb..5773bde1e1f2a65a2b6470c8835d7e3b7bba9a12 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -2707,7 +2707,9 @@ static void mg_mgr_handle_ctl_sock(struct mg_mgr *mgr) {
   struct ctl_msg ctl_msg;
   int len =
       (int) MG_RECV_FUNC(mgr->ctl[1], (char *) &ctl_msg, sizeof(ctl_msg), 0);
-  MG_SEND_FUNC(mgr->ctl[1], ctl_msg.message, 1, 0);
+  size_t dummy = MG_SEND_FUNC(mgr->ctl[1], ctl_msg.message, 1, 0);
+  (void) dummy; /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25509 */
+
   if (len >= (int) sizeof(ctl_msg.callback) && ctl_msg.callback != NULL) {
     struct mg_connection *nc;
     for (nc = mg_next(mgr, NULL); nc != NULL; nc = mg_next(mgr, nc)) {
@@ -3185,11 +3187,14 @@ void mg_broadcast(struct mg_mgr *mgr, mg_event_handler_t cb, void *data,
    */
   if (mgr->ctl[0] != INVALID_SOCKET && data != NULL &&
       len < sizeof(ctl_msg.message)) {
+    size_t dummy;
+
     ctl_msg.callback = cb;
     memcpy(ctl_msg.message, data, len);
-    MG_SEND_FUNC(mgr->ctl[0], (char *) &ctl_msg,
-                 offsetof(struct ctl_msg, message) + len, 0);
-    MG_RECV_FUNC(mgr->ctl[0], (char *) &len, 1, 0);
+    dummy = MG_SEND_FUNC(mgr->ctl[0], (char *) &ctl_msg,
+                         offsetof(struct ctl_msg, message) + len, 0);
+    dummy = MG_RECV_FUNC(mgr->ctl[0], (char *) &len, 1, 0);
+    (void) dummy;
   }
 }