diff --git a/public/java/src/org/broadinstitute/sting/utils/nanoScheduler/NanoScheduler.java b/public/java/src/org/broadinstitute/sting/utils/nanoScheduler/NanoScheduler.java
index f0c2a6723..61d4fdd01 100644
--- a/public/java/src/org/broadinstitute/sting/utils/nanoScheduler/NanoScheduler.java
+++ b/public/java/src/org/broadinstitute/sting/utils/nanoScheduler/NanoScheduler.java
@@ -210,9 +210,12 @@ public class NanoScheduler<InputType, MapType, ReduceType> {
                                              final ReduceType initialValue,
                                              final NanoSchedulerReduceFunction<MapType, ReduceType> reduce) {
         ReduceType sum = initialValue;
+        int i = 0;
         while ( inputReader.hasNext() ) {
             final InputType input = inputReader.next();
             final MapType mapValue = map.apply(input);
+            if ( i++ % bufferSize == 0 && progressFunction != null )
+                progressFunction.progress(input);
             sum = reduce.apply(mapValue, sum);
         }
         return sum;
diff --git a/public/java/test/org/broadinstitute/sting/utils/nanoScheduler/NanoSchedulerUnitTest.java b/public/java/test/org/broadinstitute/sting/utils/nanoScheduler/NanoSchedulerUnitTest.java
index 0ec3035e2..3bd006ffe 100644
--- a/public/java/test/org/broadinstitute/sting/utils/nanoScheduler/NanoSchedulerUnitTest.java
+++ b/public/java/test/org/broadinstitute/sting/utils/nanoScheduler/NanoSchedulerUnitTest.java
@@ -34,6 +34,16 @@ public class NanoSchedulerUnitTest extends BaseTest {
         }
     }
 
+    private static class ProgressCallback implements NanoSchedulerProgressFunction<Integer> {
+        int callBacks = 0;
+
+        @Override
+        public void progress(Integer lastMapInput) {
+            callBacks++;
+        }
+    }
+
+
     private static int sum2x(final int start, final int end) {
         int sum = 0;
         for ( int i = start; i < end; i++ )
@@ -62,6 +72,11 @@ public class NanoSchedulerUnitTest extends BaseTest {
             return ints.iterator();
         }
 
+        public int nExpectedCallbacks() {
+            int nElements = Math.max(end - start, 0);
+            return nElements / bufferSize;
+        }
+
         public Map2x makeMap() { return new Map2x(); }
         public Integer initReduce() { return 0; }
         public ReduceSum makeReduce() { return new ReduceSum(); }
@@ -73,7 +88,7 @@ public class NanoSchedulerUnitTest extends BaseTest {
         for ( final int bufferSize : Arrays.asList(1, 10, 1000, 1000000) ) {
             for ( final int nt : Arrays.asList(1, 2, 4) ) {
                 for ( final int start : Arrays.asList(0) ) {
-                    for ( final int end : Arrays.asList(1, 2, 11, 10000, 100000) ) {
+                    for ( final int end : Arrays.asList(0, 1, 2, 11, 10000, 100000) ) {
                         exampleTest = new NanoSchedulerBasicTest(bufferSize, nt, start, end);
                     }
                 }
@@ -101,12 +116,17 @@ public class NanoSchedulerUnitTest extends BaseTest {
         final NanoScheduler<Integer, Integer, Integer> nanoScheduler =
                 new NanoScheduler<Integer, Integer, Integer>(test.bufferSize, test.nThreads);
 
+        final ProgressCallback callback = new ProgressCallback();
+        nanoScheduler.setProgressFunction(callback);
+
         Assert.assertEquals(nanoScheduler.getBufferSize(), test.bufferSize, "bufferSize argument");
         Assert.assertEquals(nanoScheduler.getnThreads(), test.nThreads, "nThreads argument");
 
         final Integer sum = nanoScheduler.execute(test.makeReader(), test.makeMap(), test.initReduce(), test.makeReduce());
         Assert.assertNotNull(sum);
         Assert.assertEquals((int)sum, test.expectedResult, "NanoScheduler sum not the same as calculated directly");
+
+        Assert.assertTrue(callback.callBacks >= test.nExpectedCallbacks(), "Not enough callbacks detected");
         nanoScheduler.shutdown();
     }