diff --git a/examples/mapreduce-bitcoinblock/src/main/java/org/zuinnote/hadoop/bitcoin/example/driver/BitcoinBlockCounterDriver.java b/examples/mapreduce-bitcoinblock/src/main/java/org/zuinnote/hadoop/bitcoin/example/driver/BitcoinBlockCounterDriver.java
index <HASH>..<HASH> 100644
--- a/examples/mapreduce-bitcoinblock/src/main/java/org/zuinnote/hadoop/bitcoin/example/driver/BitcoinBlockCounterDriver.java
+++ b/examples/mapreduce-bitcoinblock/src/main/java/org/zuinnote/hadoop/bitcoin/example/driver/BitcoinBlockCounterDriver.java
@@ -44,8 +44,10 @@ public class BitcoinBlockCounterDriver  {
  public static void main(String[] args) throws Exception {
     JobConf conf = new JobConf(BitcoinBlockCounterDriver.class);
     conf.setJobName("example-hadoop-bitcoin-transactioncounter-job");
+    conf.setMapOutputKeyClass(Text.class);
+    conf.setMapOutputValueClass(IntWritable.class);
     conf.setOutputKeyClass(Text.class);
-    conf.setOutputValueClass(IntWritable.class);
+    conf.setOutputValueClass(LongWritable.class);
         
     conf.setMapperClass(BitcoinBlockMap.class);
     conf.setReducerClass(BitcoinBlockReducer.class);
Changed result type from int to long