diff --git a/README.md b/README.md
index 10ef068..181d6ba 100644
--- a/README.md
+++ b/README.md
@@ -707,8 +707,8 @@ kallax migrate up --dir ./my-migrations --dsn 'user:pass@localhost:5432/dbname?s
 | --- | --- |
 | `kallax.ULID` | `uuid` |
 | `kallax.UUID` | `uuid` |
-| `kallax.NumericID` | `serial` on primary keys, `bigint` on foreign keys |
-| `int64` on primary keys | `serial` |
+| `kallax.NumericID` | `bigserial` on primary keys, `bigint` on foreign keys |
+| `int64` on primary keys | `bigserial` |
 | `int64` on foreign keys and other fields| `bigint` |
 | `string` | `text` |
 | `rune` | `char(1)` |
diff --git a/generator/migration.go b/generator/migration.go
index 2149254..fecc56a 100644
--- a/generator/migration.go
+++ b/generator/migration.go
@@ -1014,7 +1014,7 @@ var typeMappings = map[string]ColumnType{
 var idTypeMappings = map[string]ColumnType{
 	"kallax.ULID":      UUIDColumn,
 	"kallax.UUID":      UUIDColumn,
-	"kallax.NumericID": SerialColumn,
+	"kallax.NumericID": BigSerialColumn,
 }
 
 func reverse(slice []string) []string {
diff --git a/generator/migration_test.go b/generator/migration_test.go
index 0dbfd60..244d9d0 100644
--- a/generator/migration_test.go
+++ b/generator/migration_test.go
@@ -602,7 +602,7 @@ type Profile struct {
 
 type ProfileMetadata struct {
 	kallax.Model ` + "`table:\"metadata\"`" + `
-	// it's an pk, should be serial
+	// it's an pk, should be bigserial
 	ID int64 ` + "`pk:\"autoincr\"`" + `
 	// a json field
 	Metadata map[string]interface{}
@@ -635,7 +635,7 @@ func (s *PackageTransformerSuite) TestTransform() {
 	expected := mkSchema(
 		mkTable(
 			"profiles",
-			mkCol("id", SerialColumn, true, true, nil),
+			mkCol("id", BigSerialColumn, true, true, nil),
 			mkCol("color", ColumnType("char(6)"), false, true, nil),
 			mkCol("background", TextColumn, false, true, nil),
 			mkCol("user_id", UUIDColumn, false, false, mkRef("users", "id", true)),
@@ -644,7 +644,7 @@ func (s *PackageTransformerSuite) TestTransform() {
 		),
 		mkTable(
 			"metadata",
-			mkCol("id", SerialColumn, true, true, nil),
+			mkCol("id", BigSerialColumn, true, true, nil),
 			mkCol("metadata", JSONBColumn, false, true, nil),
 			mkCol("profile_id", BigIntColumn, false, true, mkRef("profiles", "id", false)),
 		),