diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java
index 09007e7cb..c3423b6fb 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java
@@ -55,9 +55,10 @@
 public class TreeFilterTest extends RepositoryTestCase {
 	@Test
 	public void testALL_IncludesAnything() throws Exception {
-		final TreeWalk tw = new TreeWalk(db);
-		tw.addTree(new EmptyTreeIterator());
-		assertTrue(TreeFilter.ALL.include(tw));
+		try (final TreeWalk tw = new TreeWalk(db)) {
+			tw.addTree(new EmptyTreeIterator());
+			assertTrue(TreeFilter.ALL.include(tw));
+		}
 	}
 
 	@Test
@@ -72,16 +73,18 @@ public void testALL_IdentityClone() throws Exception {
 
 	@Test
 	public void testNotALL_IncludesNothing() throws Exception {
-		final TreeWalk tw = new TreeWalk(db);
-		tw.addTree(new EmptyTreeIterator());
-		assertFalse(TreeFilter.ALL.negate().include(tw));
+		try (final TreeWalk tw = new TreeWalk(db)) {
+			tw.addTree(new EmptyTreeIterator());
+			assertFalse(TreeFilter.ALL.negate().include(tw));
+		}
 	}
 
 	@Test
 	public void testANY_DIFF_IncludesSingleTreeCase() throws Exception {
-		final TreeWalk tw = new TreeWalk(db);
-		tw.addTree(new EmptyTreeIterator());
-		assertTrue(TreeFilter.ANY_DIFF.include(tw));
+		try (final TreeWalk tw = new TreeWalk(db)) {
+			tw.addTree(new EmptyTreeIterator());
+			assertTrue(TreeFilter.ANY_DIFF.include(tw));
+		}
 	}
 
 	@Test