diff --git a/include/juice/juice.h b/include/juice/juice.h
index b0a8eabf..9e85d800 100644
--- a/include/juice/juice.h
+++ b/include/juice/juice.h
@@ -41,6 +41,8 @@ extern "C" {
 #define JUICE_ERR_FAILED -2    // runtime error
 #define JUICE_ERR_NOT_AVAIL -3 // element not available
 #define JUICE_ERR_IGNORED -4   // ignored
+#define JUICE_ERR_AGAIN -5     // buffer full
+#define JUICE_ERR_TOO_LARGE -6 // datagram too large
 
 // ICE Agent
 
diff --git a/src/agent.c b/src/agent.c
index 099a86eb..13be4f47 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -1684,7 +1684,7 @@ int agent_send_stun_binding(juice_agent_t *agent, agent_stun_entry_t *entry, stu
 	// Direct send
 	int ret = agent_direct_send(agent, &entry->record, buffer, size, 0);
 	if (ret < 0) {
-		if (ret == SENETUNREACH)
+		if (ret == -SENETUNREACH)
 			JLOG_INFO("STUN binding failed: Network unreachable");
 		else
 			JLOG_WARN("STUN message send failed");
diff --git a/src/conn_mux.c b/src/conn_mux.c
index fb921aea..ca8baca1 100644
--- a/src/conn_mux.c
+++ b/src/conn_mux.c
@@ -522,6 +522,7 @@ int conn_mux_send(juice_agent_t *agent, const addr_record_t *dst, const char *da
 
 	int ret = udp_sendto(registry_impl->sock, data, size, dst);
 	if (ret < 0) {
+		ret = -sockerrno;
 		if (sockerrno == SEAGAIN || sockerrno == SEWOULDBLOCK)
 			JLOG_INFO("Send failed, buffer is full");
 		else if (sockerrno == SEMSGSIZE)
diff --git a/src/conn_poll.c b/src/conn_poll.c
index 3410ed2a..a8462c00 100644
--- a/src/conn_poll.c
+++ b/src/conn_poll.c
@@ -412,6 +412,7 @@ int conn_poll_send(juice_agent_t *agent, const addr_record_t *dst, const char *d
 
 	int ret = udp_sendto(conn_impl->sock, data, size, dst);
 	if (ret < 0) {
+		ret = -sockerrno;
 		if (sockerrno == SEAGAIN || sockerrno == SEWOULDBLOCK)
 			JLOG_INFO("Send failed, buffer is full");
 		else if (sockerrno == SEMSGSIZE)
diff --git a/src/conn_thread.c b/src/conn_thread.c
index 01074c17..1b054580 100644
--- a/src/conn_thread.c
+++ b/src/conn_thread.c
@@ -260,6 +260,7 @@ int conn_thread_send(juice_agent_t *agent, const addr_record_t *dst, const char
 
 	int ret = udp_sendto(conn_impl->sock, data, size, dst);
 	if (ret < 0) {
+		ret = -sockerrno;
 		if (sockerrno == SEAGAIN || sockerrno == SEWOULDBLOCK)
 			JLOG_INFO("Send failed, buffer is full");
 		else if (sockerrno == SEMSGSIZE)
diff --git a/src/juice.c b/src/juice.c
index 8ebb0fd2..70be6446 100644
--- a/src/juice.c
+++ b/src/juice.c
@@ -85,23 +85,21 @@ JUICE_EXPORT int juice_set_remote_gathering_done(juice_agent_t *agent) {
 }
 
 JUICE_EXPORT int juice_send(juice_agent_t *agent, const char *data, size_t size) {
-	if (!agent || (!data && size))
-		return JUICE_ERR_INVALID;
-
-	if (agent_send(agent, data, size, 0) < 0)
-		return JUICE_ERR_FAILED;
-
-	return JUICE_ERR_SUCCESS;
+	return juice_send_diffserv(agent, data, size, 0);
 }
 
 JUICE_EXPORT int juice_send_diffserv(juice_agent_t *agent, const char *data, size_t size, int ds) {
 	if (!agent || (!data && size))
 		return JUICE_ERR_INVALID;
 
-	if (agent_send(agent, data, size, ds) < 0)
-		return JUICE_ERR_FAILED;
-
-	return JUICE_ERR_SUCCESS;
+	int ret = agent_send(agent, data, size, ds);
+	if(ret >= 0)
+		return JUICE_ERR_SUCCESS;
+	if(ret == -SEAGAIN || ret == -SEWOULDBLOCK)
+		return JUICE_ERR_AGAIN;
+	if(ret == -SEMSGSIZE)
+		return JUICE_ERR_TOO_LARGE;
+	return JUICE_ERR_FAILED;
 }
 
 JUICE_EXPORT juice_state_t juice_get_state(juice_agent_t *agent) { return agent_get_state(agent); }