diff --git a/copy_in_response.go b/copy_in_response.go
index 4439a032..5f2595b8 100644
--- a/copy_in_response.go
+++ b/copy_in_response.go
@@ -48,6 +48,7 @@ func (src *CopyInResponse) Encode(dst []byte) []byte {
 	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)