diff --git a/src/test/examples/multidex/main-dex-rules-whyareyoukeeping.txt b/src/test/examples/multidex/main-dex-rules-whyareyoukeeping.txt
new file mode 100644
index 0000000..4a94d41
--- /dev/null
+++ b/src/test/examples/multidex/main-dex-rules-whyareyoukeeping.txt
@@ -0,0 +1,30 @@
+# Copyright (c) 2018, the R8 project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+# Keep the application entry point. Get rid of everything that is not
+# reachable from there.
+-keep public class * extends **.Instrumentation {
+  <init>();
+}
+-keep public class * extends **.Application {
+  <init>();
+  void attachBaseContext(*.Context);
+}
+-keep public class * extends **.Activity {
+  <init>();
+}
+-keep public class * extends **.Service {
+  <init>();
+}
+-keep public class * extends **.ContentProvider {
+ <init>();
+}
+-keep public class * extends **.BroadcastReceiver {
+ <init>();
+}
+-keep public class * extends **.BackupAgent {
+ <init>();
+}
+
+-whyareyoukeeping class **
diff --git a/src/test/java/com/android/tools/r8/maindexlist/MainDexTracingTest.java b/src/test/java/com/android/tools/r8/maindexlist/MainDexTracingTest.java
index bb2628a..43b4c0f 100644
--- a/src/test/java/com/android/tools/r8/maindexlist/MainDexTracingTest.java
+++ b/src/test/java/com/android/tools/r8/maindexlist/MainDexTracingTest.java
@@ -15,8 +15,12 @@
 import com.android.tools.r8.ir.desugar.LambdaRewriter;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.DescriptorUtils;
+import com.android.tools.r8.utils.FileUtils;
 import com.android.tools.r8.utils.InternalOptions;
 import com.android.tools.r8.utils.StringUtils;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -40,6 +44,23 @@
   @Rule public TemporaryFolder temp = ToolHelper.getTemporaryFolderForTest();
 
   @Test
+  public void traceMainDexList001_whyareyoukeeping() throws Throwable {
+    PrintStream stdout = System.out;
+    ByteArrayOutputStream baos = new ByteArrayOutputStream();
+    System.setOut(new PrintStream(baos));
+    doTest(
+        "traceMainDexList001_1",
+        "multidex001",
+        EXAMPLE_BUILD_DIR,
+        Paths.get(EXAMPLE_SRC_DIR, "multidex", "main-dex-rules-whyareyoukeeping.txt"),
+        Paths.get(EXAMPLE_SRC_DIR, "multidex001", "ref-list-1.txt"),
+        AndroidApiLevel.I);
+    String output = new String(baos.toByteArray(), Charset.defaultCharset());
+    Assert.assertTrue(output.contains("is live because referenced in keep rule:"));
+    System.setOut(stdout);
+  }
+
+  @Test
   public void traceMainDexList001_1() throws Throwable {
     doTest(
         "traceMainDexList001_1",
@@ -271,10 +292,9 @@
   }
 
   private String mainDexStringToDescriptor(String mainDexString) {
-    final String CLASS_EXTENSION = ".class";
-    Assert.assertTrue(mainDexString.endsWith(CLASS_EXTENSION));
+    Assert.assertTrue(mainDexString.endsWith(FileUtils.CLASS_EXTENSION));
     return DescriptorUtils.getDescriptorFromClassBinaryName(
-        mainDexString.substring(0, mainDexString.length() - CLASS_EXTENSION.length()));
+        mainDexString.substring(0, mainDexString.length() - FileUtils.CLASS_EXTENSION.length()));
   }
 
   private void checkSameMainDexEntry(String reference, String computed) {