diff --git a/nbd/server.c b/nbd/server.c
index 4752a6c8bc..c5d71cff10 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -2378,8 +2378,17 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
         if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
             flags |= BDRV_REQ_NO_FALLBACK;
         }
-        ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset,
-                                request->len, flags);
+        ret = 0;
+        /* FIXME simplify this when blk_pwrite_zeroes switches to 64-bit */
+        while (ret >= 0 && request->len) {
+            int align = client->check_align ?: 1;
+            int len = MIN(request->len, QEMU_ALIGN_DOWN(BDRV_REQUEST_MAX_BYTES,
+                                                        align));
+            ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset,
+                                    len, flags);
+            request->len -= len;
+            request->from += len;
+        }
         return nbd_send_generic_reply(client, request->handle, ret,
                                       "writing to file failed", errp);
 
@@ -2393,9 +2402,18 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
                                       "flush failed", errp);
 
     case NBD_CMD_TRIM:
-        ret = blk_co_pdiscard(exp->blk, request->from + exp->dev_offset,
-                              request->len);
-        if (ret == 0 && request->flags & NBD_CMD_FLAG_FUA) {
+        ret = 0;
+        /* FIXME simplify this when blk_co_pdiscard switches to 64-bit */
+        while (ret >= 0 && request->len) {
+            int align = client->check_align ?: 1;
+            int len = MIN(request->len, QEMU_ALIGN_DOWN(BDRV_REQUEST_MAX_BYTES,
+                                                        align));
+            ret = blk_co_pdiscard(exp->blk, request->from + exp->dev_offset,
+                                  len);
+            request->len -= len;
+            request->from += len;
+        }
+        if (ret >= 0 && request->flags & NBD_CMD_FLAG_FUA) {
             ret = blk_co_flush(exp->blk);
         }
         return nbd_send_generic_reply(client, request->handle, ret,