diff --git a/lowlevel/SyncObject.java b/lowlevel/SyncObject.java
deleted file mode 100644
index f5c88352..00000000
--- a/lowlevel/SyncObject.java
+++ /dev/null
@@ -1,41 +0,0 @@
-// lowlevel/SyncObject.java
-// (c)2017 MindView LLC: see Copyright.txt
-// We make no guarantees that this code is fit for any purpose.
-// Visit http://OnJava8.com for more book information.
-// Synchronizing on another object
-import java.util.concurrent.*;
-import onjava.Nap;
-
-class DualSynch {
-  public synchronized void f() {
-    for(int i = 0; i < 5; i++)
-      System.out.println("f() " + i);
-  }
-  private Object syncObject = new Object();
-  public void g() {
-    synchronized(syncObject) {
-      for(int i = 0; i < 5; i++)
-        System.out.println("g() " + i);
-    }
-  }
-}
-
-public class SyncObject {
-  public static void main(String[] args) {
-    DualSynch ds = new DualSynch();
-    CompletableFuture.runAsync(() -> ds.f());
-    ds.g();
-  }
-}
-/* Output:
-g() 0
-g() 1
-f() 0
-g() 2
-f() 1
-g() 3
-f() 2
-g() 4
-f() 3
-f() 4
-*/
diff --git a/lowlevel/SyncOnObject.java b/lowlevel/SyncOnObject.java
new file mode 100644
index 00000000..6151bb5c
--- /dev/null
+++ b/lowlevel/SyncOnObject.java
@@ -0,0 +1,70 @@
+// lowlevel/SyncOnObject.java
+// (c)2017 MindView LLC: see Copyright.txt
+// We make no guarantees that this code is fit for any purpose.
+// Visit http://OnJava8.com for more book information.
+// Synchronizing on another object
+import java.util.*;
+import java.util.stream.*;
+import java.util.concurrent.*;
+import onjava.Nap;
+
+class DualSynch {
+  ConcurrentLinkedQueue<String> trace =
+    new ConcurrentLinkedQueue<>();
+  public synchronized void f(boolean nap) {
+    for(int i = 0; i < 5; i++) {
+      trace.add(String.format("f() " + i));
+      if(nap) new Nap(10);
+    }
+  }
+  private Object syncObject = new Object();
+  public void g(boolean nap) {
+    synchronized(syncObject) {
+      for(int i = 0; i < 5; i++) {
+        trace.add(String.format("g() " + i));
+        if(nap) new Nap(10);
+      }
+    }
+  }
+}
+
+public class SyncOnObject {
+  static void test(boolean fNap, boolean gNap) {
+    DualSynch ds = new DualSynch();
+    List<CompletableFuture<Void>> cfs =
+      Arrays.stream(new Runnable[] {
+        () -> ds.f(fNap), () -> ds.g(gNap) })
+        .map(CompletableFuture::runAsync)
+        .collect(Collectors.toList());
+    cfs.forEach(CompletableFuture::join);
+    ds.trace.forEach(System.out::println);
+  }
+  public static void main(String[] args) {
+    test(true, false);
+    System.out.println("****");
+    test(false, true);
+  }
+}
+/* Output:
+f() 0
+g() 0
+g() 1
+g() 2
+g() 3
+g() 4
+f() 1
+f() 2
+f() 3
+f() 4
+****
+f() 0
+g() 0
+f() 1
+f() 2
+f() 3
+f() 4
+g() 1
+g() 2
+g() 3
+g() 4
+*/