diff --git a/migrations/v4.go b/migrations/v4.go
index 93bfbc1..403a3f0 100644
--- a/migrations/v4.go
+++ b/migrations/v4.go
@@ -1,46 +1,44 @@
 package migrations
 
 import (
 	"context"
 	"database/sql"
 
 	wf_db "github.com/writeas/writefreely/db"
 )
 
 func oauth(db *datastore) error {
 	dialect := wf_db.DialectMySQL
 	if db.driverName == driverSQLite {
 		dialect = wf_db.DialectSQLite
 	}
 	return wf_db.RunTransactionWithOptions(context.Background(), db.DB, &sql.TxOptions{}, func(ctx context.Context, tx *sql.Tx) error {
 		createTableUsersOauth, err := dialect.
 			Table("oauth_users").
 			SetIfNotExists(true).
 			Column(dialect.Column("user_id", wf_db.ColumnTypeInteger, wf_db.UnsetSize)).
 			Column(dialect.Column("remote_user_id", wf_db.ColumnTypeInteger, wf_db.UnsetSize)).
-			UniqueConstraint("user_id").
-			UniqueConstraint("remote_user_id").
 			ToSQL()
 		if err != nil {
 			return err
 		}
 		createTableOauthClientState, err := dialect.
 			Table("oauth_client_states").
 			SetIfNotExists(true).
 			Column(dialect.Column("state", wf_db.ColumnTypeVarChar, wf_db.OptionalInt{Set: true, Value: 255})).
 			Column(dialect.Column("used", wf_db.ColumnTypeBool, wf_db.UnsetSize)).
 			Column(dialect.Column("created_at", wf_db.ColumnTypeDateTime, wf_db.UnsetSize).SetDefaultCurrentTimestamp()).
 			UniqueConstraint("state").
 			ToSQL()
 		if err != nil {
 			return err
 		}
 
 		for _, table := range []string{createTableUsersOauth, createTableOauthClientState} {
 			if _, err := tx.ExecContext(ctx, table); err != nil {
 				return err
 			}
 		}
 		return nil
 	})
 }
diff --git a/migrations/v5.go b/migrations/v5.go
index 94e3944..0dc5129 100644
--- a/migrations/v5.go
+++ b/migrations/v5.go
@@ -1,67 +1,65 @@
 package migrations
 
 import (
 	"context"
 	"database/sql"
 
 	wf_db "github.com/writeas/writefreely/db"
 )
 
 func oauthSlack(db *datastore) error {
 	dialect := wf_db.DialectMySQL
 	if db.driverName == driverSQLite {
 		dialect = wf_db.DialectSQLite
 	}
 	return wf_db.RunTransactionWithOptions(context.Background(), db.DB, &sql.TxOptions{}, func(ctx context.Context, tx *sql.Tx) error {
 		builders := []wf_db.SQLBuilder{
 			dialect.
 				AlterTable("oauth_client_states").
 				AddColumn(dialect.
 					Column(
 						"provider",
 						wf_db.ColumnTypeVarChar,
 						wf_db.OptionalInt{Set: true, Value: 24,})).
 				AddColumn(dialect.
 					Column(
 						"client_id",
 						wf_db.ColumnTypeVarChar,
 						wf_db.OptionalInt{Set: true, Value: 128,})),
 			dialect.
 				AlterTable("oauth_users").
 				ChangeColumn("remote_user_id",
 					dialect.
 						Column(
 							"remote_user_id",
 							wf_db.ColumnTypeVarChar,
 							wf_db.OptionalInt{Set: true, Value: 128,})).
 				AddColumn(dialect.
 					Column(
 						"provider",
 						wf_db.ColumnTypeVarChar,
 						wf_db.OptionalInt{Set: true, Value: 24,})).
 				AddColumn(dialect.
 					Column(
 						"client_id",
 						wf_db.ColumnTypeVarChar,
 						wf_db.OptionalInt{Set: true, Value: 128,})).
 				AddColumn(dialect.
 					Column(
 						"access_token",
 						wf_db.ColumnTypeVarChar,
 						wf_db.OptionalInt{Set: true, Value: 512,})),
-			dialect.DropIndex("remote_user_id", "oauth_users"),
-			dialect.DropIndex("user_id", "oauth_users"),
 			dialect.CreateUniqueIndex("oauth_users", "oauth_users", "user_id", "provider", "client_id"),
 		}
 		for _, builder := range builders {
 			query, err := builder.ToSQL()
 			if err != nil {
 				return err
 			}
 			if _, err := tx.ExecContext(ctx, query); err != nil {
 				return err
 			}
 		}
 		return nil
 	})
 }