diff --git a/smt-csv/src/main/scala/org/bitlap/csv/FileUtils.scala b/smt-csv/src/main/scala/org/bitlap/csv/FileUtils.scala
index 4f902bc269e27b192593b96b478cd8d272bb6b48..6577b0e4f16cefc11462af4ee28c2819c9b9aaae 100644
--- a/smt-csv/src/main/scala/org/bitlap/csv/FileUtils.scala
+++ b/smt-csv/src/main/scala/org/bitlap/csv/FileUtils.scala
@@ -59,6 +59,7 @@ object FileUtils {
           } else {
             r.println(line)
           }
+          r.flush()
         }
       }
     finally bufferedWriter.close()