diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index 133b1d94b5..dfa02f77ee 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -34,8 +34,11 @@
  * https://github.com/yoe/nbd/blob/master/doc/proto.md
  */
 
-/* Size of all NBD_OPT_*, without payload */
+/* Size of all compact NBD_CMD_*, without payload */
 #define NBD_REQUEST_SIZE            (4 + 2 + 2 + 8 + 8 + 4)
+/* Size of all extended NBD_CMD_*, without payload */
+#define NBD_EXTENDED_REQUEST_SIZE   (4 + 2 + 2 + 8 + 8 + 8)
+
 /* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */
 #define NBD_REPLY_SIZE              (4 + 4 + 8)
 /* Size of reply to NBD_OPT_EXPORT_NAME */
diff --git a/nbd/server.c b/nbd/server.c
index 56e9b41828..501749d62b 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1411,11 +1411,13 @@ nbd_read_eof(NBDClient *client, void *buffer, size_t size, Error **errp)
 static int coroutine_fn nbd_receive_request(NBDClient *client, NBDRequest *request,
                                             Error **errp)
 {
-    uint8_t buf[NBD_REQUEST_SIZE];
-    uint32_t magic;
+    uint8_t buf[NBD_EXTENDED_REQUEST_SIZE];
+    uint32_t magic, expect;
     int ret;
+    size_t size = client->mode >= NBD_MODE_EXTENDED ?
+        NBD_EXTENDED_REQUEST_SIZE : NBD_REQUEST_SIZE;
 
-    ret = nbd_read_eof(client, buf, sizeof(buf), errp);
+    ret = nbd_read_eof(client, buf, size, errp);
     if (ret < 0) {
         return ret;
     }
@@ -1423,13 +1425,21 @@ static int coroutine_fn nbd_receive_request(NBDClient *client, NBDRequest *reque
         return -EIO;
     }
 
-    /* Request
-       [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
-       [ 4 ..  5]   flags   (NBD_CMD_FLAG_FUA, ...)
-       [ 6 ..  7]   type    (NBD_CMD_READ, ...)
-       [ 8 .. 15]   cookie
-       [16 .. 23]   from
-       [24 .. 27]   len
+    /*
+     * Compact request
+     *  [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
+     *  [ 4 ..  5]   flags   (NBD_CMD_FLAG_FUA, ...)
+     *  [ 6 ..  7]   type    (NBD_CMD_READ, ...)
+     *  [ 8 .. 15]   cookie
+     *  [16 .. 23]   from
+     *  [24 .. 27]   len
+     * Extended request
+     *  [ 0 ..  3]   magic   (NBD_EXTENDED_REQUEST_MAGIC)
+     *  [ 4 ..  5]   flags   (NBD_CMD_FLAG_FUA, NBD_CMD_FLAG_PAYLOAD_LEN, ...)
+     *  [ 6 ..  7]   type    (NBD_CMD_READ, ...)
+     *  [ 8 .. 15]   cookie
+     *  [16 .. 23]   from
+     *  [24 .. 31]   len
      */
 
     magic = ldl_be_p(buf);
@@ -1437,13 +1447,20 @@ static int coroutine_fn nbd_receive_request(NBDClient *client, NBDRequest *reque
     request->type   = lduw_be_p(buf + 6);
     request->cookie = ldq_be_p(buf + 8);
     request->from   = ldq_be_p(buf + 16);
-    request->len    = (uint32_t)ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+    if (client->mode >= NBD_MODE_EXTENDED) {
+        request->len = ldq_be_p(buf + 24);
+        expect = NBD_EXTENDED_REQUEST_MAGIC;
+    } else {
+        request->len = (uint32_t)ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+        expect = NBD_REQUEST_MAGIC;
+    }
 
     trace_nbd_receive_request(magic, request->flags, request->type,
                               request->from, request->len);
 
-    if (magic != NBD_REQUEST_MAGIC) {
-        error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
+    if (magic != expect) {
+        error_setg(errp, "invalid magic (got 0x%" PRIx32 ", expected 0x%"
+                   PRIx32 ")", magic, expect);
         return -EINVAL;
     }
     return 0;