diff --git a/helper.go b/helper.go
index 3f6f25d..3ea4e4e 100644
--- a/helper.go
+++ b/helper.go
@@ -181,7 +181,7 @@ func IsLenReader(reader io.Reader) bool {
 
 func CheckReaderLen(reader io.Reader) error {
 	nlen, err := GetReaderLen(reader)
-	if err != nil || nlen < singleUploadMaxLength {
+	if err != nil || nlen <= singleUploadMaxLength {
 		return nil
 	}
 	return errors.New("The single object size you upload can not be larger than 5GB")
diff --git a/object_part.go b/object_part.go
index 461d126..b080bcd 100644
--- a/object_part.go
+++ b/object_part.go
@@ -536,7 +536,7 @@ func (s *ObjectService) MultiCopy(ctx context.Context, name string, sourceURL st
 	if err != nil {
 		return nil, nil, err
 	}
-	if partNum == 0 || (totalBytes < singleUploadMaxLength && !opt.useMulti) {
+	if partNum == 0 || (totalBytes <= singleUploadMaxLength && !opt.useMulti) {
 		if len(id) > 0 {
 			return s.Copy(ctx, name, sourceURL, opt.OptCopy, id[0])
 		} else {