diff --git a/core/src/main/java/hudson/util/StreamTaskListener.java b/core/src/main/java/hudson/util/StreamTaskListener.java
index d70a905920..53b394b68a 100644
--- a/core/src/main/java/hudson/util/StreamTaskListener.java
+++ b/core/src/main/java/hudson/util/StreamTaskListener.java
@@ -42,6 +42,7 @@ import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import jenkins.util.SystemProperties;
 import org.kohsuke.stapler.framework.io.WriterOutputStream;
 
 import javax.annotation.CheckForNull;
@@ -166,12 +167,22 @@ public class StreamTaskListener extends AbstractTaskListener implements TaskList
     private void writeObject(ObjectOutputStream out) throws IOException {
         out.writeObject(new RemoteOutputStream(new CloseProofOutputStream(this.out)));
         out.writeObject(charset==null? null : charset.name());
+        LOGGER.log(Level.FINE, null, new Throwable("serializing here with AUTO_FLUSH=" + AUTO_FLUSH));
     }
 
+    /**
+     * Restores eager remote flushing behavior.
+     * By default, remote tasks are expected to call {@link PrintStream#flush} before exiting.
+     * This flag will ensure that no output is lost from tasks which neglect to do so,
+     * at the expense of heavier Remoting traffic and reduced performance.
+     */
+    private static /* not final */ boolean AUTO_FLUSH = SystemProperties.getBoolean(StreamTaskListener.class.getName() + ".AUTO_FLUSH");
+
     private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-        out = new PrintStream((OutputStream)in.readObject(), false);
+        out = new PrintStream((OutputStream)in.readObject(), AUTO_FLUSH);
         String name = (String)in.readObject();
         charset = name==null ? null : Charset.forName(name);
+        LOGGER.log(Level.FINE, null, new Throwable("deserializing here with AUTO_FLUSH=" + AUTO_FLUSH));
     }
 
     @Override
diff --git a/test/src/test/java/hudson/util/ArgumentListBuilder2Test.java b/test/src/test/java/hudson/util/ArgumentListBuilder2Test.java
index fe8c19f6f7..e51dd1feea 100644
--- a/test/src/test/java/hudson/util/ArgumentListBuilder2Test.java
+++ b/test/src/test/java/hudson/util/ArgumentListBuilder2Test.java
@@ -39,12 +39,14 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.jvnet.hudson.test.Email;
 import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.LoggerRule;
 
 import com.google.common.base.Joiner;
 
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.StringWriter;
+import java.util.logging.Level;
 
 /**
  * @author Kohsuke Kawaguchi
@@ -54,6 +56,9 @@ public class ArgumentListBuilder2Test {
     @Rule
     public JenkinsRule j = new JenkinsRule();
 
+    @Rule
+    public LoggerRule logging = new LoggerRule().record(StreamTaskListener.class, Level.FINE);
+
     /**
      * Makes sure {@link RemoteLauncher} properly masks arguments.
      */
@@ -64,8 +69,10 @@ public class ArgumentListBuilder2Test {
         args.add("java");
         args.addMasked("-version");
 
-        Slave s = j.createSlave();
-        s.toComputer().connect(false).get();
+        Slave s = j.createOnlineSlave();
+        /* TODO https://github.com/jenkinsci/jenkins-test-harness/pull/127
+        j.showSlaveLogs(s, logging);
+        */
 
         StringWriter out = new StringWriter();
         assertEquals(0,s.createLauncher(new StreamTaskListener(out)).launch().cmds(args).join());