diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheTest.java
new file mode 100644
index 000000000..2e7670e91
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheTest.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2017, Google Inc.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.eclipse.jgit.internal.storage.dfs;
+
+import static org.eclipse.jgit.lib.Constants.OBJ_BLOB;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.eclipse.jgit.junit.TestRng;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectInserter;
+import org.eclipse.jgit.lib.ObjectReader;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TestName;
+
+public class DfsBlockCacheTest {
+	@Rule
+	public TestName testName = new TestName();
+	private TestRng rng;
+	private DfsBlockCache cache;
+
+	@Before
+	public void setUp() {
+		rng = new TestRng(testName.getMethodName());
+		DfsBlockCache.reconfigure(new DfsBlockCacheConfig()
+				.setBlockSize(512)
+				.setBlockLimit(1 << 20));
+		cache = DfsBlockCache.getInstance();
+	}
+
+	@Test
+	public void streamKeyReusesBlocks() throws Exception {
+		DfsRepositoryDescription repo = new DfsRepositoryDescription("test");
+		InMemoryRepository r1 = new InMemoryRepository(repo);
+		byte[] content = rng.nextBytes(424242);
+		ObjectId id;
+		try (ObjectInserter ins = r1.newObjectInserter()) {
+			id = ins.insert(OBJ_BLOB, content);
+			ins.flush();
+		}
+
+		long oldSize = cache.getCurrentSize();
+		assertTrue(oldSize > 2000);
+		assertEquals(0, cache.getHitCount());
+
+		List<DfsPackDescription> packs = r1.getObjectDatabase().listPacks();
+		InMemoryRepository r2 = new InMemoryRepository(repo);
+		r2.getObjectDatabase().commitPack(packs, Collections.emptyList());
+		try (ObjectReader rdr = r2.newObjectReader()) {
+			byte[] actual = rdr.open(id, OBJ_BLOB).getBytes();
+			assertTrue(Arrays.equals(content, actual));
+		}
+		assertEquals(0, cache.getMissCount());
+		assertEquals(oldSize, cache.getCurrentSize());
+	}
+}