diff --git a/tpl/macros_struct.twig b/tpl/macros_struct.twig
index c8f1847..e6344b4 100644
--- a/tpl/macros_struct.twig
+++ b/tpl/macros_struct.twig
@@ -149,8 +149,8 @@ func Save{{ ctx.s.name }}Diff(ctx context.Context, dbe metadb.Execer, rec {{ ctx
 	values = append(values, rec.{{ f|fname }})
 	{% endfor %}
 
+	{% if ctx.raw_nonpk_fields|length > 0 %}
 	initUpdateLen := updateBuilder.Len()
-
 	{% for f in ctx.raw_nonpk_fields %}
 	if rec.{{ f|fname }}Changed() {
 		queryBuilder.WriteString(",`{{ f.name }}`")
@@ -164,6 +164,7 @@ func Save{{ ctx.s.name }}Diff(ctx context.Context, dbe metadb.Execer, rec {{ ctx
 		values = append(values, rec.{{ f|fname }})
 	}
 	{% endfor %}
+	{% endif %}
 
 	{% if has_token(ctx.s, 'table_json_kv') %}
 	var jsonBuilder strings.Builder