diff --git a/spark/src/main/scala/com/alibaba/graphar/util/FileSystem.scala b/spark/src/main/scala/com/alibaba/graphar/util/FileSystem.scala
index d1f69e096..0575e104f 100644
--- a/spark/src/main/scala/com/alibaba/graphar/util/FileSystem.scala
+++ b/spark/src/main/scala/com/alibaba/graphar/util/FileSystem.scala
@@ -109,6 +109,7 @@ object FileSystem {
     // consistent with c++ library, convert to little-endian
     output.writeLong(java.lang.Long.reverseBytes(value))
     output.close()
+    fs.close()
   }
 
   def readValue(inputPath: String, hadoopConfig: Configuration): Long = {