diff --git a/connection_util.go b/connection_util.go
index 4ab3e8344..a8b20726e 100644
--- a/connection_util.go
+++ b/connection_util.go
@@ -165,11 +165,11 @@ func getFileStream(ctx context.Context) (*bytes.Buffer, error) {
 
 	// read a small amount of data to check if file stream will be used
 	buf := make([]byte, defaultStringBufferSize)
-	_, err := r.Read(buf)
+	n, err := r.Read(buf)
 	if err != nil {
 		return nil, err
 	}
-	return bytes.NewBuffer(buf), nil
+	return bytes.NewBuffer(buf[:n]), nil
 }
 
 func getFileTransferOptions(ctx context.Context) *SnowflakeFileTransferOptions {