diff --git a/scripts-available/CDB_CartodbfyTable.sql b/scripts-available/CDB_CartodbfyTable.sql
index 849238e..4d44c22 100644
--- a/scripts-available/CDB_CartodbfyTable.sql
+++ b/scripts-available/CDB_CartodbfyTable.sql
@@ -152,12 +152,12 @@ BEGIN
       -- Copy existing values to new field
       -- NOTE: using ALTER is a workaround to a PostgreSQL bug and is also known to be faster for tables with many rows
       -- See http://www.postgresql.org/message-id/20140530143150.GA11051@localhost
-      sql := Format('ALTER TABLE %s ALTER cartodb_id TYPE int USING %I', reloid::text, new_name);
+      sql := Format('ALTER TABLE %s ALTER cartodb_id TYPE int USING %I::integer', reloid::text, new_name);
       RAISE DEBUG 'Running %', sql;
       EXECUTE sql;
 
       -- Find max value
-      sql := Format('SELECT max(cartodb_id) FROM %s', reloid::text);
+      sql := Format('SELECT coalesce(max(cartodb_id), 0) as max FROM %s', reloid::text);
       RAISE DEBUG 'Running %', sql;
       EXECUTE sql INTO rec;
 
@@ -166,7 +166,7 @@ BEGIN
         AS seq INTO rec2;
 
       -- Reset sequence name
-      sql := Format('ALTER SEQUENCE %s RESTART WITH %d', rec2.seq::text, rec.max + 1);
+      sql := Format('ALTER SEQUENCE %s RESTART WITH %s', rec2.seq::text, rec.max + 1);
       RAISE DEBUG 'Running %', sql;
       EXECUTE sql;
 
diff --git a/test/CDB_CartodbfyTableTest.sql b/test/CDB_CartodbfyTableTest.sql
index fc6bd8a..76e62b0 100644
--- a/test/CDB_CartodbfyTableTest.sql
+++ b/test/CDB_CartodbfyTableTest.sql
@@ -319,6 +319,23 @@ SELECT CDB_CartodbfyTableCheck('test', 'Table with non unique and null cartodb_i
 SELECT cartodb_id, cartodb_id_0 from test;
 DROP TABLE test;
 
+SET client_min_messages TO notice;
+-- _CDB_create_cartodb_id_column with cartodb_id integer already present
+CREATE TABLE test (cartodb_id integer);
+
+SELECT _CDB_Create_Cartodb_ID_Column('test'::regclass);
+SELECT column_name FROM information_schema.columns WHERE table_name = 'test' AND column_name = '_cartodb_id0';
+
+DROP TABLE test;
+
+-- _CDB_create_cartodb_id_column with cartodb_id text already present
+CREATE TABLE test (cartodb_id text);
+
+SELECT _CDB_Create_Cartodb_ID_Column('test'::regclass);
+SELECT column_name FROM information_schema.columns WHERE table_name = 'test' AND column_name = '_cartodb_id0';
+
+DROP TABLE test;
+SET client_min_messages TO error;
 
 -- TODO: table with existing custom-triggered the_geom
 
diff --git a/test/CDB_CartodbfyTableTest_expect b/test/CDB_CartodbfyTableTest_expect
index 6103dc8..e63dbd3 100644
--- a/test/CDB_CartodbfyTableTest_expect
+++ b/test/CDB_CartodbfyTableTest_expect
@@ -102,5 +102,19 @@ Table with non unique and null cartodb_id #148 cartodbfied fine
 3|
 4|2
 DROP TABLE
+SET
+CREATE TABLE
+NOTICE:  Column cartodb_id already exists
+NOTICE:  Existing cartodb_id field does not have an associated sequence, renaming
+NOTICE:  Trying to recover data from _cartodb_id0 column
+
+DROP TABLE
+CREATE TABLE
+NOTICE:  Column cartodb_id already exists
+NOTICE:  Existing cartodb_id field is of invalid type text (need int2, int4 or int8), renaming
+NOTICE:  Trying to recover data from _cartodb_id0 column
+
+DROP TABLE
+SET
 DROP FUNCTION
 DROP FUNCTION