diff --git a/nbd.c b/nbd.c
index 1df2b91bf2fdad03b6ceb4e9808808340c7b3850..d8cc331a0baccbbadc813dd80d8fb00b3054baf1 100644
--- a/nbd.c
+++ b/nbd.c
@@ -585,7 +585,7 @@ static int nbd_send_reply(int csock, struct nbd_reply *reply)
 
 int nbd_trip(BlockDriverState *bs, int csock, off_t size,
              uint64_t dev_offset, uint32_t nbdflags,
-             uint8_t *data, int data_size)
+             uint8_t *data)
 {
     struct nbd_request request;
     struct nbd_reply reply;
@@ -596,9 +596,9 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
     if (nbd_receive_request(csock, &request) == -1)
         return -1;
 
-    if (request.len + NBD_REPLY_SIZE > data_size) {
+    if (request.len + NBD_REPLY_SIZE > NBD_BUFFER_SIZE) {
         LOG("len (%u) is larger than max len (%u)",
-            request.len + NBD_REPLY_SIZE, data_size);
+            request.len + NBD_REPLY_SIZE, NBD_BUFFER_SIZE);
         errno = EINVAL;
         return -1;
     }
diff --git a/nbd.h b/nbd.h
index ebdb2dbf41e3462007122d028c2e702e31bfa448..dbc4c0d627363a99611872b8e499e2f68ae2d6d2 100644
--- a/nbd.h
+++ b/nbd.h
@@ -57,6 +57,8 @@ enum {
 
 #define NBD_DEFAULT_PORT	10809
 
+#define NBD_BUFFER_SIZE (1024*1024)
+
 size_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
 int tcp_socket_outgoing(const char *address, uint16_t port);
 int tcp_socket_incoming(const char *address, uint16_t port);
@@ -72,7 +74,7 @@ int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize);
 int nbd_send_request(int csock, struct nbd_request *request);
 int nbd_receive_reply(int csock, struct nbd_reply *reply);
 int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset,
-             uint32_t nbdflags, uint8_t *data, int data_size);
+             uint32_t nbdflags, uint8_t *data);
 int nbd_client(int fd);
 int nbd_disconnect(int fd);
 
diff --git a/qemu-nbd.c b/qemu-nbd.c
index f9ee9c58d1e2594324e9965f6ba6c3a2ee0a72ff..d662268c812998b2d5262065127523d426b7fbbb 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -35,8 +35,6 @@
 
 #define SOCKET_PATH    "/var/lock/qemu-nbd-%s"
 
-#define NBD_BUFFER_SIZE (1024*1024)
-
 static int sigterm_wfd;
 static int verbose;
 static char *device;
@@ -541,7 +539,7 @@ int main(int argc, char **argv)
         for (i = 1; i < nb_fds && ret; i++) {
             if (FD_ISSET(sharing_fds[i], &fds)) {
                 if (nbd_trip(bs, sharing_fds[i], fd_size, dev_offset,
-                    nbdflags, data, NBD_BUFFER_SIZE) != 0) {
+                             nbdflags, data) != 0) {
                     close(sharing_fds[i]);
                     nb_fds--;
                     sharing_fds[i] = sharing_fds[nb_fds];