diff --git a/services/tasks/src/main/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollection.java b/services/tasks/src/main/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollection.java
index 49e8d1da7a..5cb0b12cf3 100644
--- a/services/tasks/src/main/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollection.java
+++ b/services/tasks/src/main/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollection.java
@@ -25,6 +25,7 @@ import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Function;
 
+import com.google.common.annotations.VisibleForTesting;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -39,7 +40,7 @@ public class FlatFileTaskCollection<T> implements TaskCollection<T> {
   private final Function<BytesValue, T> deserializer;
   private final long rollWhenFileSizeExceedsBytes;
 
-  private final ByteBuffer lengthBuffer = ByteBuffer.allocate(Integer.SIZE);
+  private final ByteBuffer lengthBuffer = ByteBuffer.allocate(Integer.BYTES);
 
   private FileChannel readFileChannel;
   private FileChannel writeFileChannel;
@@ -135,13 +136,13 @@ public class FlatFileTaskCollection<T> implements TaskCollection<T> {
   private void writeTaskData(final BytesValue data) throws IOException {
     final long offset = writeFileChannel.size();
     writeDataLength(data.size(), offset);
-    writeFileChannel.write(ByteBuffer.wrap(data.getArrayUnsafe()), offset + Integer.SIZE);
+    writeFileChannel.write(ByteBuffer.wrap(data.getArrayUnsafe()), offset + Integer.BYTES);
   }
 
   private int readDataLength() throws IOException {
     lengthBuffer.position(0);
-    lengthBuffer.limit(Integer.SIZE);
-    readBytes(lengthBuffer, Integer.SIZE);
+    lengthBuffer.limit(Integer.BYTES);
+    readBytes(lengthBuffer, Integer.BYTES);
     return lengthBuffer.getInt(0);
   }
 
@@ -182,6 +183,16 @@ public class FlatFileTaskCollection<T> implements TaskCollection<T> {
     return size() == 0;
   }
 
+  @VisibleForTesting
+  int getReadFileNumber() {
+    return readFileNumber;
+  }
+
+  @VisibleForTesting
+  int getWriteFileNumber() {
+    return writeFileNumber;
+  }
+
   @Override
   public synchronized void clear() {
     outstandingTasks.clear();
diff --git a/services/tasks/src/test/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollectionTest.java b/services/tasks/src/test/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollectionTest.java
index 28e16b6ea4..9c8e1cfd93 100644
--- a/services/tasks/src/test/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollectionTest.java
+++ b/services/tasks/src/test/java/tech/pegasys/pantheon/services/tasks/FlatFileTaskCollectionTest.java
@@ -16,7 +16,6 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 import tech.pegasys.pantheon.util.bytes.BytesValue;
 
-import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.ArrayList;
@@ -51,20 +50,19 @@ public class FlatFileTaskCollectionTest
       final List<BytesValue> tasks = new ArrayList<>();
 
       addItem(queue, tasks, 0);
-      final File[] currentFiles = getCurrentFiles(dataDir);
-      assertThat(currentFiles).hasSize(1);
-      final File firstFile = currentFiles[0];
+      assertThat(queue.getWriteFileNumber()).isEqualTo(0);
       int tasksInFirstFile = 1;
-      while (getCurrentFiles(dataDir).length == 1) {
+      while (queue.getWriteFileNumber() == 0) {
         addItem(queue, tasks, tasksInFirstFile);
         tasksInFirstFile++;
       }
 
-      assertThat(getCurrentFiles(dataDir)).hasSizeGreaterThan(1);
-      assertThat(getCurrentFiles(dataDir)).contains(firstFile);
+      assertThat(queue.getWriteFileNumber()).isGreaterThan(0);
+      assertThat(queue.getReadFileNumber()).isEqualTo(0);
 
-      // Add an extra item to be sure we have at least one in a later file
+      // Add extra items to be sure we have at least one in a later file
       addItem(queue, tasks, 123);
+      addItem(queue, tasks, 124);
 
       final List<BytesValue> removedTasks = new ArrayList<>();
       // Read through all the items in the first file.
@@ -72,8 +70,9 @@ public class FlatFileTaskCollectionTest
         removedTasks.add(queue.remove().getData());
       }
 
-      // Fully read files should have been removed.
-      assertThat(getCurrentFiles(dataDir)).doesNotContain(firstFile);
+      // read one more to make sure we are reading from the next file
+      removedTasks.add(queue.remove().getData());
+      assertThat(queue.getReadFileNumber()).isEqualTo(1);
 
       // Check that all tasks were read correctly.
       removedTasks.add(queue.remove().getData());
@@ -89,10 +88,4 @@ public class FlatFileTaskCollectionTest
     tasks.add(BytesValue.of(value));
     queue.add(BytesValue.of(value));
   }
-
-  private File[] getCurrentFiles(final Path dataDir) {
-    return dataDir
-        .toFile()
-        .listFiles((dir, name) -> name.startsWith(FlatFileTaskCollection.FILENAME_PREFIX));
-  }
 }