diff --git a/skynet-src/skynet_socket.c b/skynet-src/skynet_socket.c
index f2dff1cc..3f2c9a04 100644
--- a/skynet-src/skynet_socket.c
+++ b/skynet-src/skynet_socket.c
@@ -107,7 +107,6 @@ skynet_socket_poll() {
 static int
 check_wsz(struct skynet_context *ctx, int id, void *buffer, int64_t wsz) {
 	if (wsz < 0) {
-		skynet_free(buffer);
 		return -1;
 	} else if (wsz > 1024 * 1024) {
 		int kb4 = wsz / 1024 / 4;
diff --git a/skynet-src/socket_server.c b/skynet-src/socket_server.c
index eba07624..7c287b90 100644
--- a/skynet-src/socket_server.c
+++ b/skynet-src/socket_server.c
@@ -1286,11 +1286,19 @@ socket_server_connect(struct socket_server *ss, uintptr_t opaque, const char * a
 	return request.u.open.id;
 }
 
+static void
+free_buffer(struct socket_server *ss, const void * buffer, int sz) {
+	struct send_object so;
+	send_object_init(ss, &so, (void *)buffer, sz);
+	so.free_func((void *)buffer);
+}
+
 // return -1 when error
 int64_t 
 socket_server_send(struct socket_server *ss, int id, const void * buffer, int sz) {
 	struct socket * s = &ss->slot[HASH_ID(id)];
 	if (s->id != id || s->type == SOCKET_TYPE_INVALID) {
+		free_buffer(ss, buffer, sz);
 		return -1;
 	}
 
@@ -1307,6 +1315,7 @@ void
 socket_server_send_lowpriority(struct socket_server *ss, int id, const void * buffer, int sz) {
 	struct socket * s = &ss->slot[HASH_ID(id)];
 	if (s->id != id || s->type == SOCKET_TYPE_INVALID) {
+		free_buffer(ss, buffer, sz);
 		return;
 	}
 
@@ -1489,6 +1498,7 @@ int64_t
 socket_server_udp_send(struct socket_server *ss, int id, const struct socket_udp_address *addr, const void *buffer, int sz) {
 	struct socket * s = &ss->slot[HASH_ID(id)];
 	if (s->id != id || s->type == SOCKET_TYPE_INVALID) {
+		free_buffer(ss, buffer, sz);
 		return -1;
 	}
 
@@ -1507,6 +1517,7 @@ socket_server_udp_send(struct socket_server *ss, int id, const struct socket_udp
 		addrsz = 1+2+16;	// 1 type, 2 port, 16 ipv6
 		break;
 	default:
+		free_buffer(ss, buffer, sz);
 		return -1;
 	}