diff --git a/copy_both_response.go b/copy_both_response.go
index fbd985d8..4a1c3a07 100644
--- a/copy_both_response.go
+++ b/copy_both_response.go
@@ -48,7 +48,7 @@ func (src *CopyBothResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'W')
 	sp := len(dst)
 	dst = pgio.AppendInt32(dst, -1)
-
+	dst = append(dst, src.OverallFormat)
 	dst = pgio.AppendUint16(dst, uint16(len(src.ColumnFormatCodes)))
 	for _, fc := range src.ColumnFormatCodes {
 		dst = pgio.AppendUint16(dst, fc)