diff --git a/src/virglrenderer.c b/src/virglrenderer.c
index a0d173a..9836691 100644
--- a/src/virglrenderer.c
+++ b/src/virglrenderer.c
@@ -884,6 +884,10 @@ int virgl_renderer_resource_create_blob(const struct virgl_renderer_resource_cre
    if (args->res_handle == 0)
       return -EINVAL;
 
+   /* user resource id must be unique */
+   if (virgl_resource_lookup(args->res_handle))
+      return -EINVAL;
+
    if (args->size == 0)
       return -EINVAL;
    if (has_guest_storage) {
@@ -1042,6 +1046,10 @@ virgl_renderer_resource_import_blob(const struct virgl_renderer_resource_import_
    if (args->res_handle == 0)
       return -EINVAL;
 
+   /* user resource id must be unique */
+   if (virgl_resource_lookup(args->res_handle))
+      return -EINVAL;
+
    switch (args->blob_mem) {
    case VIRGL_RENDERER_BLOB_MEM_HOST3D:
    case VIRGL_RENDERER_BLOB_MEM_GUEST_VRAM: