diff --git a/libasn1parser/asn1p_class.c b/libasn1parser/asn1p_class.c
index 4376089..a025f36 100644
--- a/libasn1parser/asn1p_class.c
+++ b/libasn1parser/asn1p_class.c
@@ -27,11 +27,13 @@
 
 void
 asn1p_ioc_table_append(asn1p_ioc_table_t *it, asn1p_ioc_table_t *src) {
+    int base_idx;
 
-    if(!src) return;
+    if(!src || !it) return;
 
+    base_idx = it->rows;
     for(size_t i = 0; i < src->rows; i++) {
-        asn1p_ioc_table_add(it, asn1p_ioc_row_clone(src->row[i]));
+        asn1p_ioc_table_add(it, asn1p_ioc_row_clone(src->row[i], base_idx));
     }
 }
 
@@ -104,7 +106,7 @@
 }
 
 asn1p_ioc_row_t *
-asn1p_ioc_row_clone(asn1p_ioc_row_t *src) {
+asn1p_ioc_row_clone(asn1p_ioc_row_t *src, int base_idx) {
 	asn1p_ioc_row_t *row;
 
 	row = calloc(1, sizeof *row);
@@ -119,7 +121,11 @@
 
 	for(size_t i = 0; i < src->columns; i++) {
 		row->column[i].field = src->column[i].field;
-		row->column[i].value = src->column[i].value ? asn1p_expr_clone(src->column[i].value, 0) : 0;
+		row->column[i].value = 0;
+		if(src->column[i].value) {
+			row->column[i].value = asn1p_expr_clone(src->column[i].value, 0);
+			row->column[i].value->_type_unique_index += base_idx;
+		}
 		row->column[i].new_ref = 1;
 	}