diff --git a/public/java/test/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegionsUnitTest.java b/public/java/test/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegionsUnitTest.java
index e82dc28e1..4cda1455e 100644
--- a/public/java/test/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegionsUnitTest.java
+++ b/public/java/test/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegionsUnitTest.java
@@ -241,6 +241,21 @@ public class TraverseActiveRegionsUnitTest extends BaseTest {
         Assert.assertEquals(intervalStops.size(), 0, "Interval stop location does not match an active region stop location");
     }
 
+    @Test
+    public void testActiveRegionExtensionOnContig() {
+        DummyActiveRegionWalker walker = new DummyActiveRegionWalker();
+
+        Collection<ActiveRegion> activeRegions = getActiveRegions(walker, intervals).values();
+        for (ActiveRegion activeRegion : activeRegions) {
+            GenomeLoc loc = activeRegion.getExtendedLoc();
+
+            // Contract: active region extensions must stay on the contig
+            Assert.assertTrue(loc.getStart() > 0, "Active region extension begins at location " + loc.getStart() + ", past the left end of the contig");
+            int refLen = dictionary.getSequence(loc.getContigIndex()).getSequenceLength();
+            Assert.assertTrue(loc.getStop() <= refLen, "Active region extension ends at location " + loc.getStop() + ", past the right end of the contig");
+        }
+    }
+
     @Test
     public void testPrimaryReadMapping() {
         DummyActiveRegionWalker walker = new DummyActiveRegionWalker();