diff --git a/internal/endtoend/testdata/enum_alter_change/mysql/go/db.go b/internal/endtoend/testdata/enum_alter_change/mysql/go/db.go
new file mode 100644
index 0000000000..57406b68e8
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_change/mysql/go/db.go
@@ -0,0 +1,31 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.20.0
+
+package querytest
+
+import (
+	"context"
+	"database/sql"
+)
+
+type DBTX interface {
+	ExecContext(context.Context, string, ...interface{}) (sql.Result, error)
+	PrepareContext(context.Context, string) (*sql.Stmt, error)
+	QueryContext(context.Context, string, ...interface{}) (*sql.Rows, error)
+	QueryRowContext(context.Context, string, ...interface{}) *sql.Row
+}
+
+func New(db DBTX) *Queries {
+	return &Queries{db: db}
+}
+
+type Queries struct {
+	db DBTX
+}
+
+func (q *Queries) WithTx(tx *sql.Tx) *Queries {
+	return &Queries{
+		db: tx,
+	}
+}
diff --git a/internal/endtoend/testdata/enum_alter_change/mysql/go/models.go b/internal/endtoend/testdata/enum_alter_change/mysql/go/models.go
new file mode 100644
index 0000000000..3af0810506
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_change/mysql/go/models.go
@@ -0,0 +1,60 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.20.0
+
+package querytest
+
+import (
+	"database/sql/driver"
+	"fmt"
+)
+
+type AuthorsStatus string
+
+const (
+	AuthorsStatusInit       AuthorsStatus = "init"
+	AuthorsStatusDone       AuthorsStatus = "done"
+	AuthorsStatusCanceled   AuthorsStatus = "canceled"
+	AuthorsStatusProcessing AuthorsStatus = "processing"
+	AuthorsStatusWaiting    AuthorsStatus = "waiting"
+)
+
+func (e *AuthorsStatus) Scan(src interface{}) error {
+	switch s := src.(type) {
+	case []byte:
+		*e = AuthorsStatus(s)
+	case string:
+		*e = AuthorsStatus(s)
+	default:
+		return fmt.Errorf("unsupported scan type for AuthorsStatus: %T", src)
+	}
+	return nil
+}
+
+type NullAuthorsStatus struct {
+	AuthorsStatus AuthorsStatus
+	Valid         bool // Valid is true if AuthorsStatus is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (ns *NullAuthorsStatus) Scan(value interface{}) error {
+	if value == nil {
+		ns.AuthorsStatus, ns.Valid = "", false
+		return nil
+	}
+	ns.Valid = true
+	return ns.AuthorsStatus.Scan(value)
+}
+
+// Value implements the driver Valuer interface.
+func (ns NullAuthorsStatus) Value() (driver.Value, error) {
+	if !ns.Valid {
+		return nil, nil
+	}
+	return string(ns.AuthorsStatus), nil
+}
+
+type Author struct {
+	ID     int64
+	Status AuthorsStatus
+}
diff --git a/internal/endtoend/testdata/enum_alter_change/mysql/go/query.sql.go b/internal/endtoend/testdata/enum_alter_change/mysql/go/query.sql.go
new file mode 100644
index 0000000000..ccac241cd6
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_change/mysql/go/query.sql.go
@@ -0,0 +1,37 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.20.0
+// source: query.sql
+
+package querytest
+
+import (
+	"context"
+)
+
+const listAuthors = `-- name: ListAuthors :many
+select id, status from authors
+`
+
+func (q *Queries) ListAuthors(ctx context.Context) ([]Author, error) {
+	rows, err := q.db.QueryContext(ctx, listAuthors)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Author
+	for rows.Next() {
+		var i Author
+		if err := rows.Scan(&i.ID, &i.Status); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
diff --git a/internal/endtoend/testdata/enum_alter_change/mysql/query.sql b/internal/endtoend/testdata/enum_alter_change/mysql/query.sql
new file mode 100644
index 0000000000..0b16d94be6
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_change/mysql/query.sql
@@ -0,0 +1,2 @@
+-- name: ListAuthors :many
+select * from authors;
diff --git a/internal/endtoend/testdata/enum_alter_change/mysql/schema.sql b/internal/endtoend/testdata/enum_alter_change/mysql/schema.sql
new file mode 100644
index 0000000000..67c89a0eff
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_change/mysql/schema.sql
@@ -0,0 +1,9 @@
+-- similar to issue https://github.com/sqlc-dev/sqlc/issues/1503
+
+CREATE TABLE authors (
+  id   bigint primary key,
+  status enum("ok", "init") default "init" not null
+);
+
+-- remove this alter to see the change in models.go
+ALTER TABLE authors CHANGE status status enum('init', 'done', 'canceled', 'processing', 'waiting') default "init" not null;
\ No newline at end of file
diff --git a/internal/endtoend/testdata/enum_alter_change/mysql/sqlc.json b/internal/endtoend/testdata/enum_alter_change/mysql/sqlc.json
new file mode 100644
index 0000000000..feb988c2be
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_change/mysql/sqlc.json
@@ -0,0 +1,13 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "name": "querytest",
+      "path": "go",
+      "schema": "schema.sql",
+      "queries": "query.sql",
+      "engine": "mysql",
+      "omit_unused_structs": true
+    }
+  ]
+}
diff --git a/internal/endtoend/testdata/enum_alter_modify/mysql/go/db.go b/internal/endtoend/testdata/enum_alter_modify/mysql/go/db.go
new file mode 100644
index 0000000000..57406b68e8
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_modify/mysql/go/db.go
@@ -0,0 +1,31 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.20.0
+
+package querytest
+
+import (
+	"context"
+	"database/sql"
+)
+
+type DBTX interface {
+	ExecContext(context.Context, string, ...interface{}) (sql.Result, error)
+	PrepareContext(context.Context, string) (*sql.Stmt, error)
+	QueryContext(context.Context, string, ...interface{}) (*sql.Rows, error)
+	QueryRowContext(context.Context, string, ...interface{}) *sql.Row
+}
+
+func New(db DBTX) *Queries {
+	return &Queries{db: db}
+}
+
+type Queries struct {
+	db DBTX
+}
+
+func (q *Queries) WithTx(tx *sql.Tx) *Queries {
+	return &Queries{
+		db: tx,
+	}
+}
diff --git a/internal/endtoend/testdata/enum_alter_modify/mysql/go/models.go b/internal/endtoend/testdata/enum_alter_modify/mysql/go/models.go
new file mode 100644
index 0000000000..3af0810506
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_modify/mysql/go/models.go
@@ -0,0 +1,60 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.20.0
+
+package querytest
+
+import (
+	"database/sql/driver"
+	"fmt"
+)
+
+type AuthorsStatus string
+
+const (
+	AuthorsStatusInit       AuthorsStatus = "init"
+	AuthorsStatusDone       AuthorsStatus = "done"
+	AuthorsStatusCanceled   AuthorsStatus = "canceled"
+	AuthorsStatusProcessing AuthorsStatus = "processing"
+	AuthorsStatusWaiting    AuthorsStatus = "waiting"
+)
+
+func (e *AuthorsStatus) Scan(src interface{}) error {
+	switch s := src.(type) {
+	case []byte:
+		*e = AuthorsStatus(s)
+	case string:
+		*e = AuthorsStatus(s)
+	default:
+		return fmt.Errorf("unsupported scan type for AuthorsStatus: %T", src)
+	}
+	return nil
+}
+
+type NullAuthorsStatus struct {
+	AuthorsStatus AuthorsStatus
+	Valid         bool // Valid is true if AuthorsStatus is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (ns *NullAuthorsStatus) Scan(value interface{}) error {
+	if value == nil {
+		ns.AuthorsStatus, ns.Valid = "", false
+		return nil
+	}
+	ns.Valid = true
+	return ns.AuthorsStatus.Scan(value)
+}
+
+// Value implements the driver Valuer interface.
+func (ns NullAuthorsStatus) Value() (driver.Value, error) {
+	if !ns.Valid {
+		return nil, nil
+	}
+	return string(ns.AuthorsStatus), nil
+}
+
+type Author struct {
+	ID     int64
+	Status AuthorsStatus
+}
diff --git a/internal/endtoend/testdata/enum_alter_modify/mysql/go/query.sql.go b/internal/endtoend/testdata/enum_alter_modify/mysql/go/query.sql.go
new file mode 100644
index 0000000000..ccac241cd6
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_modify/mysql/go/query.sql.go
@@ -0,0 +1,37 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.20.0
+// source: query.sql
+
+package querytest
+
+import (
+	"context"
+)
+
+const listAuthors = `-- name: ListAuthors :many
+select id, status from authors
+`
+
+func (q *Queries) ListAuthors(ctx context.Context) ([]Author, error) {
+	rows, err := q.db.QueryContext(ctx, listAuthors)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Author
+	for rows.Next() {
+		var i Author
+		if err := rows.Scan(&i.ID, &i.Status); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
diff --git a/internal/endtoend/testdata/enum_alter_modify/mysql/query.sql b/internal/endtoend/testdata/enum_alter_modify/mysql/query.sql
new file mode 100644
index 0000000000..0b16d94be6
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_modify/mysql/query.sql
@@ -0,0 +1,2 @@
+-- name: ListAuthors :many
+select * from authors;
diff --git a/internal/endtoend/testdata/enum_alter_modify/mysql/schema.sql b/internal/endtoend/testdata/enum_alter_modify/mysql/schema.sql
new file mode 100644
index 0000000000..d199af185f
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_modify/mysql/schema.sql
@@ -0,0 +1,9 @@
+-- similar to issue https://github.com/sqlc-dev/sqlc/issues/1503
+
+CREATE TABLE authors (
+  id   bigint primary key,
+  status enum("ok", "init") default "init" not null
+);
+
+-- remove this alter to see the change in models.go
+ALTER TABLE authors MODIFY status enum('init', 'done', 'canceled', 'processing', 'waiting') default "init" not null;
\ No newline at end of file
diff --git a/internal/endtoend/testdata/enum_alter_modify/mysql/sqlc.json b/internal/endtoend/testdata/enum_alter_modify/mysql/sqlc.json
new file mode 100644
index 0000000000..feb988c2be
--- /dev/null
+++ b/internal/endtoend/testdata/enum_alter_modify/mysql/sqlc.json
@@ -0,0 +1,13 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "name": "querytest",
+      "path": "go",
+      "schema": "schema.sql",
+      "queries": "query.sql",
+      "engine": "mysql",
+      "omit_unused_structs": true
+    }
+  ]
+}
diff --git a/internal/engine/dolphin/convert.go b/internal/engine/dolphin/convert.go
index 5cca536976..a167858e4c 100644
--- a/internal/engine/dolphin/convert.go
+++ b/internal/engine/dolphin/convert.go
@@ -43,20 +43,10 @@ func (c *cc) convertAlterTableStmt(n *pcast.AlterTableStmt) ast.Node {
 		case pcast.AlterTableAddColumns:
 			for _, def := range spec.NewColumns {
 				name := def.Name.String()
-				columnDef := ast.ColumnDef{
-					Colname:    def.Name.String(),
-					TypeName:   &ast.TypeName{Name: types.TypeToStr(def.Tp.GetType(), def.Tp.GetCharset())},
-					IsNotNull:  isNotNull(def),
-					IsUnsigned: isUnsigned(def),
-				}
-				if def.Tp.GetFlen() >= 0 {
-					length := def.Tp.GetFlen()
-					columnDef.Length = &length
-				}
 				alt.Cmds.Items = append(alt.Cmds.Items, &ast.AlterTableCmd{
 					Name:    &name,
 					Subtype: ast.AT_AddColumn,
-					Def:     &columnDef,
+					Def:     convertColumnDef(def),
 				})
 			}
 
@@ -77,36 +67,16 @@ func (c *cc) convertAlterTableStmt(n *pcast.AlterTableStmt) ast.Node {
 
 			for _, def := range spec.NewColumns {
 				name := def.Name.String()
-				columnDef := ast.ColumnDef{
-					Colname:    def.Name.String(),
-					TypeName:   &ast.TypeName{Name: types.TypeToStr(def.Tp.GetType(), def.Tp.GetCharset())},
-					IsNotNull:  isNotNull(def),
-					IsUnsigned: isUnsigned(def),
-				}
-				if def.Tp.GetFlen() >= 0 {
-					length := def.Tp.GetFlen()
-					columnDef.Length = &length
-				}
 				alt.Cmds.Items = append(alt.Cmds.Items, &ast.AlterTableCmd{
 					Name:    &name,
 					Subtype: ast.AT_AddColumn,
-					Def:     &columnDef,
+					Def:     convertColumnDef(def),
 				})
 			}
 
 		case pcast.AlterTableModifyColumn:
 			for _, def := range spec.NewColumns {
 				name := def.Name.String()
-				columnDef := ast.ColumnDef{
-					Colname:    def.Name.String(),
-					TypeName:   &ast.TypeName{Name: types.TypeToStr(def.Tp.GetType(), def.Tp.GetCharset())},
-					IsNotNull:  isNotNull(def),
-					IsUnsigned: isUnsigned(def),
-				}
-				if def.Tp.GetFlen() >= 0 {
-					length := def.Tp.GetFlen()
-					columnDef.Length = &length
-				}
 				alt.Cmds.Items = append(alt.Cmds.Items, &ast.AlterTableCmd{
 					Name:    &name,
 					Subtype: ast.AT_DropColumn,
@@ -114,7 +84,7 @@ func (c *cc) convertAlterTableStmt(n *pcast.AlterTableStmt) ast.Node {
 				alt.Cmds.Items = append(alt.Cmds.Items, &ast.AlterTableCmd{
 					Name:    &name,
 					Subtype: ast.AT_AddColumn,
-					Def:     &columnDef,
+					Def:     convertColumnDef(def),
 				})
 			}
 
@@ -249,37 +219,7 @@ func (c *cc) convertCreateTableStmt(n *pcast.CreateTableStmt) ast.Node {
 		create.ReferTable = parseTableName(n.ReferTable)
 	}
 	for _, def := range n.Cols {
-		var vals *ast.List
-		if len(def.Tp.GetElems()) > 0 {
-			vals = &ast.List{}
-			for i := range def.Tp.GetElems() {
-				vals.Items = append(vals.Items, &ast.String{
-					Str: def.Tp.GetElems()[i],
-				})
-			}
-		}
-		comment := ""
-		for _, opt := range def.Options {
-			switch opt.Tp {
-			case pcast.ColumnOptionComment:
-				if value, ok := opt.Expr.(*driver.ValueExpr); ok {
-					comment = value.GetString()
-				}
-			}
-		}
-		columnDef := ast.ColumnDef{
-			Colname:    def.Name.String(),
-			TypeName:   &ast.TypeName{Name: types.TypeToStr(def.Tp.GetType(), def.Tp.GetCharset())},
-			IsNotNull:  isNotNull(def),
-			IsUnsigned: isUnsigned(def),
-			Comment:    comment,
-			Vals:       vals,
-		}
-		if def.Tp.GetFlen() >= 0 {
-			length := def.Tp.GetFlen()
-			columnDef.Length = &length
-		}
-		create.Cols = append(create.Cols, &columnDef)
+		create.Cols = append(create.Cols, convertColumnDef(def))
 	}
 	for _, opt := range n.Options {
 		switch opt.Tp {
@@ -290,6 +230,41 @@ func (c *cc) convertCreateTableStmt(n *pcast.CreateTableStmt) ast.Node {
 	return create
 }
 
+func convertColumnDef(def *pcast.ColumnDef) *ast.ColumnDef {
+	var vals *ast.List
+	if len(def.Tp.GetElems()) > 0 {
+		vals = &ast.List{}
+		for i := range def.Tp.GetElems() {
+			vals.Items = append(vals.Items, &ast.String{
+				Str: def.Tp.GetElems()[i],
+			})
+		}
+	}
+	comment := ""
+	for _, opt := range def.Options {
+		switch opt.Tp {
+		case pcast.ColumnOptionComment:
+			if value, ok := opt.Expr.(*driver.ValueExpr); ok {
+				comment = value.GetString()
+			}
+		}
+	}
+	columnDef := ast.ColumnDef{
+		Colname:    def.Name.String(),
+		TypeName:   &ast.TypeName{Name: types.TypeToStr(def.Tp.GetType(), def.Tp.GetCharset())},
+		IsNotNull:  isNotNull(def),
+		IsUnsigned: isUnsigned(def),
+		Comment:    comment,
+		Vals:       vals,
+	}
+	if def.Tp.GetFlen() >= 0 {
+		length := def.Tp.GetFlen()
+		columnDef.Length = &length
+	}
+
+	return &columnDef
+}
+
 func (c *cc) convertColumnNameExpr(n *pcast.ColumnNameExpr) *ast.ColumnRef {
 	var items []ast.Node
 	if schema := n.Name.Schema.String(); schema != "" {
diff --git a/internal/sql/catalog/catalog.go b/internal/sql/catalog/catalog.go
index 278ea8797d..9a4a29e880 100644
--- a/internal/sql/catalog/catalog.go
+++ b/internal/sql/catalog/catalog.go
@@ -83,7 +83,7 @@ func (c *Catalog) Update(stmt ast.Statement, colGen columnGenerator) error {
 		err = c.createCompositeType(n)
 
 	case *ast.CreateEnumStmt:
-		err = c.createEnum(n)
+		err = c.createEnum(n, false)
 
 	case *ast.CreateExtensionStmt:
 		err = c.createExtension(n)
diff --git a/internal/sql/catalog/table.go b/internal/sql/catalog/table.go
index 5598da4df5..1c9bacf994 100644
--- a/internal/sql/catalog/table.go
+++ b/internal/sql/catalog/table.go
@@ -41,7 +41,7 @@ func (table *Table) isExistColumn(cmd *ast.AlterTableCmd) (int, error) {
 	return -1, nil
 }
 
-func (table *Table) addColumn(cmd *ast.AlterTableCmd) error {
+func (table *Table) addColumn(c *Catalog, cmd *ast.AlterTableCmd) error {
 	for _, c := range table.Columns {
 		if c.Name == cmd.Def.Colname {
 			if !cmd.MissingOk {
@@ -51,15 +51,12 @@ func (table *Table) addColumn(cmd *ast.AlterTableCmd) error {
 		}
 	}
 
-	table.Columns = append(table.Columns, &Column{
-		Name:       cmd.Def.Colname,
-		Type:       *cmd.Def.TypeName,
-		IsNotNull:  cmd.Def.IsNotNull,
-		IsUnsigned: cmd.Def.IsUnsigned,
-		IsArray:    cmd.Def.IsArray,
-		ArrayDims:  cmd.Def.ArrayDims,
-		Length:     cmd.Def.Length,
-	})
+	tc, err := c.defToColumn(table.Rel, cmd.Def)
+	if err != nil {
+		return err
+	}
+
+	table.Columns = append(table.Columns, tc)
 	return nil
 }
 
@@ -187,7 +184,7 @@ func (c *Catalog) alterTable(stmt *ast.AlterTableStmt) error {
 		case *ast.AlterTableCmd:
 			switch cmd.Subtype {
 			case ast.AT_AddColumn:
-				if err := table.addColumn(cmd); err != nil {
+				if err := table.addColumn(c, cmd); err != nil {
 					return err
 				}
 			case ast.AT_AlterColumnType:
@@ -305,25 +302,9 @@ func (c *Catalog) createTable(stmt *ast.CreateTableStmt) error {
 				continue
 			}
 
-			tc := &Column{
-				Name:       col.Colname,
-				Type:       *col.TypeName,
-				IsNotNull:  col.IsNotNull,
-				IsUnsigned: col.IsUnsigned,
-				IsArray:    col.IsArray,
-				ArrayDims:  col.ArrayDims,
-				Comment:    col.Comment,
-				Length:     col.Length,
-			}
-			if col.Vals != nil {
-				typeName := ast.TypeName{
-					Name: fmt.Sprintf("%s_%s", stmt.Name.Name, col.Colname),
-				}
-				s := &ast.CreateEnumStmt{TypeName: &typeName, Vals: col.Vals}
-				if err := c.createEnum(s); err != nil {
-					return err
-				}
-				tc.Type = typeName
+			tc, err := c.defToColumn(stmt.Name, col)
+			if err != nil {
+				return err
 			}
 			tbl.Columns = append(tbl.Columns, tc)
 		}
@@ -340,6 +321,31 @@ func (c *Catalog) createTable(stmt *ast.CreateTableStmt) error {
 	return nil
 }
 
+func (c *Catalog) defToColumn(table *ast.TableName, col *ast.ColumnDef) (*Column, error) {
+	tc := &Column{
+		Name:       col.Colname,
+		Type:       *col.TypeName,
+		IsNotNull:  col.IsNotNull,
+		IsUnsigned: col.IsUnsigned,
+		IsArray:    col.IsArray,
+		ArrayDims:  col.ArrayDims,
+		Comment:    col.Comment,
+		Length:     col.Length,
+	}
+	if col.Vals != nil {
+		typeName := ast.TypeName{
+			Name: fmt.Sprintf("%s_%s", table.Name, col.Colname),
+		}
+		s := &ast.CreateEnumStmt{TypeName: &typeName, Vals: col.Vals}
+		if err := c.createEnum(s, true); err != nil {
+			return nil, err
+		}
+		tc.Type = typeName
+	}
+
+	return tc, nil
+}
+
 func (c *Catalog) dropTable(stmt *ast.DropTableStmt) error {
 	for _, name := range stmt.Tables {
 		ns := name.Schema
diff --git a/internal/sql/catalog/types.go b/internal/sql/catalog/types.go
index e92a3a219e..2bb1033b3a 100644
--- a/internal/sql/catalog/types.go
+++ b/internal/sql/catalog/types.go
@@ -3,6 +3,7 @@ package catalog
 import (
 	"errors"
 	"fmt"
+
 	"github.com/sqlc-dev/sqlc/internal/sql/ast"
 	"github.com/sqlc-dev/sqlc/internal/sql/sqlerr"
 )
@@ -61,7 +62,7 @@ func sameType(a, b *ast.TypeName) bool {
 	return true
 }
 
-func (c *Catalog) createEnum(stmt *ast.CreateEnumStmt) error {
+func (c *Catalog) createEnum(stmt *ast.CreateEnumStmt, overwrite bool) error {
 	ns := stmt.TypeName.Schema
 	if ns == "" {
 		ns = c.DefaultSchema
@@ -80,8 +81,18 @@ func (c *Catalog) createEnum(stmt *ast.CreateEnumStmt) error {
 	if _, _, err := schema.getTable(tbl); err == nil {
 		return sqlerr.RelationExists(tbl.Name)
 	}
-	if _, _, err := schema.getType(stmt.TypeName); err == nil {
-		return sqlerr.TypeExists(tbl.Name)
+	if typ, _, err := schema.getType(stmt.TypeName); err == nil {
+		if !overwrite {
+			return sqlerr.TypeExists(tbl.Name)
+		}
+
+		enum, ok := typ.(*Enum)
+		if !ok {
+			return fmt.Errorf("type is not an enum: %s", stmt.TypeName.Name)
+		}
+		enum.Vals = stringSlice(stmt.Vals)
+
+		return nil
 	}
 	schema.Types = append(schema.Types, &Enum{
 		Name: stmt.TypeName.Name,