diff --git a/src/gallium/auxiliary/util/u_prim_restart.c b/src/gallium/auxiliary/util/u_prim_restart.c
index aea0c0c58cd..be31163ca1c 100644
--- a/src/gallium/auxiliary/util/u_prim_restart.c
+++ b/src/gallium/auxiliary/util/u_prim_restart.c
@@ -125,13 +125,14 @@ util_translate_prim_restart_ib(struct pipe_context *context,
    /* Create new index buffer */
    *dst_buffer = pipe_buffer_create(screen, PIPE_BIND_INDEX_BUFFER,
                                     PIPE_USAGE_STREAM,
-                                    count * dst_index_size);
+                                    (start + count) * dst_index_size);
    if (!*dst_buffer)
       goto error;
 
    /* Map new / dest index buffer */
-   dst_map = pipe_buffer_map(context, *dst_buffer,
-                             PIPE_MAP_WRITE, &dst_transfer);
+   dst_map = pipe_buffer_map_range(context, *dst_buffer,
+                                   start * dst_index_size, count * dst_index_size,
+                                   PIPE_MAP_WRITE, &dst_transfer);
    if (!dst_map)
       goto error;
 
@@ -148,7 +149,7 @@ util_translate_prim_restart_ib(struct pipe_context *context,
       goto error;
 
    util_translate_prim_restart_data(src_index_size, src_map, dst_map,
-                                    draw->count, info->restart_index);
+                                    count, info->restart_index);
 
    if (src_transfer)
       pipe_buffer_unmap(context, src_transfer);