diff --git a/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorHelper.java b/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorHelper.java
index 3c9225a5ead..852334b2a69 100644
--- a/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorHelper.java
+++ b/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorHelper.java
@@ -25,5 +25,12 @@ import io.druid.server.coordinator.DruidCoordinatorRuntimeParams;
  */
 public interface DruidCoordinatorHelper
 {
-  public DruidCoordinatorRuntimeParams run(DruidCoordinatorRuntimeParams params);
+  /**
+   * Implementations of this method run various activities performed by the coordinator.
+   * Input params can be used and modified. They are typically in a list and returned
+   * DruidCoordinatorRuntimeParams is passed to the next helper.
+   * @param params
+   * @return same as input or a modified value to be used by next helper.
+   */
+  DruidCoordinatorRuntimeParams run(DruidCoordinatorRuntimeParams params);
 }
diff --git a/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorSegmentKiller.java b/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorSegmentKiller.java
index 2a3ff15e4b2..aa9333552fc 100644
--- a/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorSegmentKiller.java
+++ b/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorSegmentKiller.java
@@ -19,9 +19,11 @@
 
 package io.druid.server.coordinator.helper;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.metamx.common.logger.Logger;
 import io.druid.client.indexing.IndexingServiceClient;
+import io.druid.common.utils.JodaUtils;
 import io.druid.metadata.MetadataSegmentManager;
 import io.druid.server.coordinator.DruidCoordinatorRuntimeParams;
 import org.joda.time.Duration;
@@ -100,7 +102,8 @@ public class DruidCoordinatorSegmentKiller implements DruidCoordinatorHelper
     return params;
   }
 
-  private Interval findIntervalForKillTask(String dataSource, int limit)
+  @VisibleForTesting
+  Interval findIntervalForKillTask(String dataSource, int limit)
   {
     List<Interval> unusedSegmentIntervals = segmentManager.getUnusedSegmentIntervals(
         dataSource,
@@ -113,20 +116,7 @@ public class DruidCoordinatorSegmentKiller implements DruidCoordinatorHelper
     );
 
     if (unusedSegmentIntervals != null && unusedSegmentIntervals.size() > 0) {
-      long start = Long.MIN_VALUE;
-      long end = Long.MAX_VALUE;
-
-      for (Interval interval : unusedSegmentIntervals) {
-        if (start < interval.getStartMillis()) {
-          start = interval.getStartMillis();
-        }
-
-        if (end > interval.getEndMillis()) {
-          end = interval.getEndMillis();
-        }
-      }
-
-      return new Interval(start, end);
+      return JodaUtils.umbrellaInterval(unusedSegmentIntervals);
     } else {
       return null;
     }
diff --git a/server/src/test/java/io/druid/server/coordinator/helper/DruidCoordinatorSegmentKillerTest.java b/server/src/test/java/io/druid/server/coordinator/helper/DruidCoordinatorSegmentKillerTest.java
new file mode 100644
index 00000000000..819446dcaea
--- /dev/null
+++ b/server/src/test/java/io/druid/server/coordinator/helper/DruidCoordinatorSegmentKillerTest.java
@@ -0,0 +1,113 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.druid.server.coordinator.helper;
+
+import com.google.common.collect.ImmutableList;
+import io.druid.client.indexing.IndexingServiceClient;
+import io.druid.metadata.MetadataSegmentManager;
+import org.easymock.EasyMock;
+import org.joda.time.Duration;
+import org.joda.time.Interval;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.List;
+
+/**
+ */
+public class DruidCoordinatorSegmentKillerTest
+{
+  @Test
+  public void testFindIntervalForKillTask()
+  {
+    testFindIntervalForKillTask(null, null);
+    testFindIntervalForKillTask(ImmutableList.<Interval>of(), null);
+
+    testFindIntervalForKillTask(ImmutableList.<Interval>of(Interval.parse("2014/2015")), Interval.parse("2014/2015"));
+
+    testFindIntervalForKillTask(
+        ImmutableList.<Interval>of(Interval.parse("2014/2015"), Interval.parse("2016/2017")),
+        Interval.parse("2014/2017")
+    );
+
+    testFindIntervalForKillTask(
+        ImmutableList.<Interval>of(Interval.parse("2014/2015"), Interval.parse("2015/2016")),
+        Interval.parse("2014/2016")
+    );
+
+    testFindIntervalForKillTask(
+        ImmutableList.<Interval>of(Interval.parse("2015/2016"), Interval.parse("2014/2015")),
+        Interval.parse("2014/2016")
+    );
+
+    testFindIntervalForKillTask(
+        ImmutableList.<Interval>of(Interval.parse("2015/2017"), Interval.parse("2014/2016")),
+        Interval.parse("2014/2017")
+    );
+
+    testFindIntervalForKillTask(
+        ImmutableList.<Interval>of(
+            Interval.parse("2015/2019"),
+            Interval.parse("2014/2016"),
+            Interval.parse("2018/2020")
+        ),
+        Interval.parse("2014/2020")
+    );
+
+    testFindIntervalForKillTask(
+        ImmutableList.<Interval>of(
+            Interval.parse("2015/2019"),
+            Interval.parse("2014/2016"),
+            Interval.parse("2018/2020"),
+            Interval.parse("2021/2022")
+        ),
+        Interval.parse("2014/2022")
+    );
+  }
+
+  private void testFindIntervalForKillTask(List<Interval> segmentManagerResult, Interval expected)
+  {
+    MetadataSegmentManager segmentManager = EasyMock.createMock(MetadataSegmentManager.class);
+    EasyMock.expect(
+        segmentManager.getUnusedSegmentIntervals(
+            EasyMock.anyString(),
+            EasyMock.anyObject(Interval.class),
+            EasyMock.anyInt()
+        )
+    ).andReturn(
+        segmentManagerResult
+    );
+    EasyMock.replay(segmentManager);
+    IndexingServiceClient indexingServiceClient = EasyMock.createMock(IndexingServiceClient.class);
+
+    DruidCoordinatorSegmentKiller coordinatorSegmentKiller = new DruidCoordinatorSegmentKiller(
+        segmentManager,
+        indexingServiceClient,
+        Duration.parse("PT86400S"),
+        Duration.parse("PT86400S"),
+        1000
+    );
+
+    Assert.assertEquals(
+        expected,
+        coordinatorSegmentKiller.findIntervalForKillTask("test", 10000)
+    );
+  }
+}