diff --git a/go/logic/inspect.go b/go/logic/inspect.go
index a562102..83b778a 100644
--- a/go/logic/inspect.go
+++ b/go/logic/inspect.go
@@ -192,6 +192,9 @@ func (this *Inspector) inspectOriginalAndGhostTables() (err error) {
 			this.migrationContext.MappedSharedColumns.SetEnumToTextConversion(column.Name)
 			this.migrationContext.MappedSharedColumns.SetEnumValues(column.Name, column.EnumValues)
 		}
+		if column.Name == mappedColumn.Name && column.Charset != mappedColumn.Charset {
+			this.migrationContext.SharedColumns.SetCharsetConversion(column.Name, column.Charset, mappedColumn.Charset)
+		}
 	}
 
 	for _, column := range this.migrationContext.UniqueKey.Columns.Columns() {
diff --git a/go/sql/types.go b/go/sql/types.go
index 3c4ce5e..3be1a44 100644
--- a/go/sql/types.go
+++ b/go/sql/types.go
@@ -32,6 +32,11 @@ type TimezoneConversion struct {
 	ToTimezone string
 }
 
+type CharacterSetConversion struct {
+	ToCharset   string
+	FromCharset string
+}
+
 type Column struct {
 	Name                 string
 	IsUnsigned           bool
@@ -43,17 +48,22 @@ type Column struct {
 	// add Octet length for binary type, fix bytes with suffix "00" get clipped in mysql binlog.
 	// https://github.com/github/gh-ost/issues/909
 	BinaryOctetLength uint
+	charsetConversion *CharacterSetConversion
 }
 
 func (this *Column) convertArg(arg interface{}, isUniqueKeyColumn bool) interface{} {
 	if s, ok := arg.(string); ok {
-		// string, charset conversion
-		if encoding, ok := charsetEncodingMap[this.Charset]; ok {
-			arg, _ = encoding.NewDecoder().String(s)
+		arg2Bytes := []byte(s)
+		// convert to bytes if character string without charsetConversion.
+		if this.Charset != "" && this.charsetConversion == nil {
+			arg = arg2Bytes
+		} else {
+			if encoding, ok := charsetEncodingMap[this.Charset]; ok {
+				arg, _ = encoding.NewDecoder().String(s)
+			}
 		}
 
 		if this.Type == BinaryColumnType && isUniqueKeyColumn {
-			arg2Bytes := []byte(arg.(string))
 			size := len(arg2Bytes)
 			if uint(size) < this.BinaryOctetLength {
 				buf := bytes.NewBuffer(arg2Bytes)
@@ -238,6 +248,10 @@ func (this *ColumnList) Len() int {
 	return len(this.columns)
 }
 
+func (this *ColumnList) SetCharsetConversion(columnName string, fromCharset string, toCharset string) {
+	this.GetColumn(columnName).charsetConversion = &CharacterSetConversion{FromCharset: fromCharset, ToCharset: toCharset}
+}
+
 // UniqueKey is the combination of a key's name and columns
 type UniqueKey struct {
 	Name            string