diff --git a/chain.go b/chain.go
index 1f21de39..ed2b8012 100644
--- a/chain.go
+++ b/chain.go
@@ -8,7 +8,7 @@ import (
 
 type Chain struct {
 	d          *DB
-	db         sql_common
+	db         sqlCommon
 	value      interface{}
 	debug_mode bool
 
@@ -228,9 +228,9 @@ func (s *Chain) Related(value interface{}, foreign_keys ...string) *Chain {
 }
 
 func (s *Chain) Begin() *Chain {
-	if db, ok := s.db.(sql_db); ok {
+	if db, ok := s.db.(sqlDb); ok {
 		tx, err := db.Begin()
-		s.db = interface{}(tx).(sql_common)
+		s.db = interface{}(tx).(sqlCommon)
 		s.err(err)
 	} else {
 		s.err(errors.New("Can't start a transaction."))
@@ -245,7 +245,7 @@ func (s *Chain) Debug() *Chain {
 }
 
 func (s *Chain) Commit() *Chain {
-	if db, ok := s.db.(sql_tx); ok {
+	if db, ok := s.db.(sqlTx); ok {
 		s.err(db.Commit())
 	} else {
 		s.err(errors.New("Commit is not supported, no database transaction found."))
@@ -254,7 +254,7 @@ func (s *Chain) Commit() *Chain {
 }
 
 func (s *Chain) Rollback() *Chain {
-	if db, ok := s.db.(sql_tx); ok {
+	if db, ok := s.db.(sqlTx); ok {
 		s.err(db.Rollback())
 	} else {
 		s.err(errors.New("Rollback is not supported, no database transaction found."))
diff --git a/do.go b/do.go
index b2507ce9..a1324adb 100644
--- a/do.go
+++ b/do.go
@@ -14,7 +14,7 @@ import (
 
 type Do struct {
 	chain              *Chain
-	db                 sql_common
+	db                 sqlCommon
 	guessedTableName   string
 	specifiedTableName string
 	startedTransaction bool
@@ -711,9 +711,9 @@ func (s *Do) autoMigrate() *Do {
 }
 
 func (s *Do) begin() *Do {
-	if db, ok := s.db.(sql_db); ok {
+	if db, ok := s.db.(sqlDb); ok {
 		if tx, err := db.Begin(); err == nil {
-			s.db = interface{}(tx).(sql_common)
+			s.db = interface{}(tx).(sqlCommon)
 			s.startedTransaction = true
 		}
 	}
@@ -722,7 +722,7 @@ func (s *Do) begin() *Do {
 
 func (s *Do) commit_or_rollback() {
 	if s.startedTransaction {
-		if db, ok := s.db.(sql_tx); ok {
+		if db, ok := s.db.(sqlTx); ok {
 			if s.chain.hasError() {
 				db.Rollback()
 			} else {
diff --git a/main.go b/main.go
index 218ccbc7..0f0ea4db 100644
--- a/main.go
+++ b/main.go
@@ -11,7 +11,7 @@ func init() {
 }
 
 type DB struct {
-	db      sql_common
+	db      sqlCommon
 	dialect dialect.Dialect
 	logger  Logger
 	logMode bool
@@ -24,7 +24,7 @@ func Open(driver, source string) (db DB, err error) {
 }
 
 func (s *DB) SetPool(n int) {
-	if db, ok := s.db.(sql_db); ok {
+	if db, ok := s.db.(sqlDb); ok {
 		db.SetMaxIdleConns(n)
 	}
 }
diff --git a/sql.go b/sql.go
index 3933f4aa..ac781db5 100644
--- a/sql.go
+++ b/sql.go
@@ -2,19 +2,19 @@ package gorm
 
 import "database/sql"
 
-type sqlcommon interface {
+type sqlCommon interface {
 	Exec(query string, args ...interface{}) (sql.Result, error)
 	Prepare(query string) (*sql.Stmt, error)
 	Query(query string, args ...interface{}) (*sql.Rows, error)
 	QueryRow(query string, args ...interface{}) *sql.Row
 }
 
-type sql_db interface {
+type sqlDb interface {
 	Begin() (*sql.Tx, error)
 	SetMaxIdleConns(n int)
 }
 
-type sql_tx interface {
+type sqlTx interface {
 	Commit() error
 	Rollback() error
 }