diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
index 30196d2..090a6eb 100644
--- a/hw/smbios/smbios.c
+++ b/hw/smbios/smbios.c
@@ -1411,6 +1411,14 @@
     return true;
 }
 
+static void smbios_add_usr_blob_size(size_t size)
+{
+    if (!usr_blobs_sizes) {
+        usr_blobs_sizes = g_array_new(false, false, sizeof(size_t));
+    }
+    g_array_append_val(usr_blobs_sizes, size);
+}
+
 void smbios_entry_add(QemuOpts *opts, Error **errp)
 {
     const char *val;
@@ -1458,10 +1466,12 @@
             smbios_type4_count++;
         }
 
-        if (!usr_blobs_sizes) {
-            usr_blobs_sizes = g_array_new(false, false, sizeof(size_t));
-        }
-        g_array_append_val(usr_blobs_sizes, size);
+        /*
+         * preserve blob size for legacy mode so it could build its
+         * blobs flavor from 'usr_blobs'
+         */
+        smbios_add_usr_blob_size(size);
+
         usr_blobs_len += size;
         if (size > usr_table_max) {
             usr_table_max = size;