diff --git a/examples/gcoap/client.c b/examples/gcoap/client.c
index f4dc8aaa9be6..b58c48f178cb 100644
--- a/examples/gcoap/client.c
+++ b/examples/gcoap/client.c
@@ -66,8 +66,8 @@ static size_t obs_req_tkl = 0;
 uint16_t req_count = 0;
 
 static gcoap_socket_type_t _get_tl(const char *uri);
-static size_t _send(uint8_t *buf, size_t len, const sock_udp_ep_t *remote,
-                    void *ctx, gcoap_socket_type_t tl);
+static ssize_t _send(uint8_t *buf, size_t len, const sock_udp_ep_t *remote,
+                     void *ctx, gcoap_socket_type_t tl);
 
 /*
  * Response callback.
@@ -172,10 +172,10 @@ static gcoap_socket_type_t _get_tl(const char *uri)
     return GCOAP_SOCKET_TYPE_UNDEF;
 }
 
-static size_t _send(uint8_t *buf, size_t len, const sock_udp_ep_t *remote,
-                    void *ctx, gcoap_socket_type_t tl)
+static ssize_t _send(uint8_t *buf, size_t len, const sock_udp_ep_t *remote,
+                     void *ctx, gcoap_socket_type_t tl)
 {
-    size_t bytes_sent = gcoap_req_send(buf, len, remote, _resp_handler, ctx, tl);
+    ssize_t bytes_sent = gcoap_req_send(buf, len, remote, _resp_handler, ctx, tl);
     if (bytes_sent > 0) {
         req_count++;
     }
@@ -389,8 +389,8 @@ int gcoap_cli_cmd(int argc, char **argv)
 
         printf("gcoap_cli: sending msg ID %u, %" PRIuSIZE " bytes\n",
                 coap_get_id(&pdu), len);
-        if (!_send(&buf[0], len, *_proxy_uri ? &_proxy_remote : &remote, NULL,
-                   *_proxy_uri ? _get_tl(_proxy_uri) : _get_tl(_last_req_uri))) {
+        if (_send(&buf[0], len, *_proxy_uri ? &_proxy_remote : &remote, NULL,
+                   *_proxy_uri ? _get_tl(_proxy_uri) : _get_tl(_last_req_uri)) <= 0) {
             puts("gcoap_cli: msg send failed");
         }
         else {