diff --git a/core/src/main/java/hudson/model/Computer.java b/core/src/main/java/hudson/model/Computer.java
index e30f5c390acadde493ae9b65a806eb16a06fdc4a..4ce4a3b7a39db9ac05bf9c7b02023a7c29662e5a 100644
--- a/core/src/main/java/hudson/model/Computer.java
+++ b/core/src/main/java/hudson/model/Computer.java
@@ -2,7 +2,8 @@
  * The MIT License
  *
  * Copyright (c) 2004-2010, Sun Microsystems, Inc., Kohsuke Kawaguchi,
- * Red Hat, Inc., Seiji Sogabe, Stephen Connolly, Thomas J. Black, Tom Huybrechts, CloudBees, Inc.
+ * Red Hat, Inc., Seiji Sogabe, Stephen Connolly, Thomas J. Black, Tom Huybrechts,
+ * CloudBees, Inc., Christopher Simons
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -1384,13 +1385,19 @@ public /*transient*/ abstract class Computer extends Actionable implements Acces
     public void doConfigSubmit( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException, FormException {
         checkPermission(CONFIGURE);
 
-        String name = Util.fixEmptyAndTrim(req.getSubmittedForm().getString("name"));
-        Jenkins.checkGoodName(name);
+        String proposedName = Util.fixEmptyAndTrim(req.getSubmittedForm().getString("name"));
+        Jenkins.checkGoodName(proposedName);
 
         Node node = getNode();
         if (node == null) {
             throw new ServletException("No such node " + nodeName);
         }
+
+        if ((!proposedName.equals(nodeName))
+                && Jenkins.getActiveInstance().getNode(proposedName) != null) {
+            throw new FormException(Messages.ComputerSet_SlaveAlreadyExists(proposedName), "name");
+        }
+
         Node result = node.reconfigure(req, req.getSubmittedForm());
         replaceBy(result);
 
diff --git a/test/src/test/java/hudson/model/ComputerTest.java b/test/src/test/java/hudson/model/ComputerTest.java
index b58b00f45e5380a80177ef0eb47d8f782f84d4da..8b6efad4138f23a7b2d4721a5d38730ef84a17e9 100644
--- a/test/src/test/java/hudson/model/ComputerTest.java
+++ b/test/src/test/java/hudson/model/ComputerTest.java
@@ -1,7 +1,7 @@
 /*
  * The MIT License
  *
- * Copyright (c) 2015 Red Hat, Inc.
+ * Copyright (c) 2015 Red Hat, Inc.; Christopher Simons
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -23,16 +23,26 @@
  */
 package hudson.model;
 
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.*;
 
+import com.gargoylesoftware.htmlunit.FailingHttpStatusCodeException;
+import com.gargoylesoftware.htmlunit.html.HtmlForm;
+import com.gargoylesoftware.htmlunit.html.HtmlPage;
+
 import java.io.File;
 
 import jenkins.model.Jenkins;
 import hudson.slaves.DumbSlave;
 
+import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
+import org.jvnet.hudson.test.Issue;
 import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.JenkinsRule.WebClient;
 
 public class ComputerTest {
 
@@ -52,4 +62,29 @@ public class ComputerTest {
 
         assertTrue("Slave log should be kept", keep.toComputer().getLogFile().exists());
     }
+
+    /**
+     * Verify we can't rename a node over an existing node.
+     */
+    @Issue("JENKINS-31321")
+    @Test
+    public void testProhibitRenameOverExistingNode() throws Exception {
+        final String NOTE = "Rename node to name of another node should fail.";
+
+        Node nodeA = j.createSlave("nodeA", null, null);
+        Node nodeB = j.createSlave("nodeB", null, null);
+
+        WebClient wc = j.createWebClient();
+        HtmlForm form = wc.getPage(nodeB, "configure").getFormByName("config");
+        form.getInputByName("_.name").setValueAttribute("nodeA");
+
+        try {
+            j.submit(form);
+            fail(NOTE);
+        } catch (FailingHttpStatusCodeException e) {
+            assertThat(NOTE, e.getStatusCode(), equalTo(400));
+            assertThat(NOTE, e.getResponse().getContentAsString(),
+                    containsString("Slave called ‘nodeA’ already exists"));
+        }
+    }
 }