diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 6e80de9ef5a..9642050aaeb 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -77,6 +77,9 @@ Trunk (Unreleased)
     MAPREDUCE-5196. Add bookkeeping for managing checkpoints of task state.
     (Carlo Curino via cdouglas)
 
+    MAPREDUCE-5912. Task.calculateOutputSize does not handle Windows files after
+    MAPREDUCE-5196. (Remus Rusanu via cnauroth)
+
   BUG FIXES
 
     MAPREDUCE-5714. Removed forceful JVM exit in shutDownJob.  
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java
index 72cd41c9ea6..4815f191f7e 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java
@@ -1120,8 +1120,8 @@ abstract public class Task implements Writable, Configurable {
     if (isMapTask() && conf.getNumReduceTasks() > 0) {
       try {
         Path mapOutput =  mapOutputFile.getOutputFile();
-        FileSystem fs = mapOutput.getFileSystem(conf);
-        return fs.getFileStatus(mapOutput).getLen();
+        FileSystem localFS = FileSystem.getLocal(conf);
+        return localFS.getFileStatus(mapOutput).getLen();
       } catch (IOException e) {
         LOG.warn ("Could not find output size " , e);
       }