diff --git a/dialect.go b/dialect.go
index 8c950da0..70420ee5 100644
--- a/dialect.go
+++ b/dialect.go
@@ -287,7 +287,7 @@ func (b *Base) LogSQL(sql string, args []interface{}) {
 }
 
 var (
-	dialects = map[DbType]func() Dialect{}
+	dialects = map[string]func() Dialect{}
 )
 
 // RegisterDialect register database dialect
@@ -295,12 +295,12 @@ func RegisterDialect(dbName DbType, dialectFunc func() Dialect) {
 	if dialectFunc == nil {
 		panic("core: Register dialect is nil")
 	}
-	dialects[dbName] = dialectFunc // !nashtsai! allow override dialect
+	dialects[strings.ToLower(string(dbName))] = dialectFunc // !nashtsai! allow override dialect
 }
 
 // QueryDialect query if registed database dialect
 func QueryDialect(dbName DbType) Dialect {
-	if d, ok := dialects[dbName]; ok {
+	if d, ok := dialects[strings.ToLower(string(dbName))]; ok {
 		return d()
 	}
 	return nil