diff --git a/core/src/main/java/hudson/model/ComputerSet.java b/core/src/main/java/hudson/model/ComputerSet.java
index 20218badb806ffd1d50cd90bf7062c404cc2d16b..e167ac3f3866b721ea449dbbd7a07081e4aad370 100644
--- a/core/src/main/java/hudson/model/ComputerSet.java
+++ b/core/src/main/java/hudson/model/ComputerSet.java
@@ -211,7 +211,7 @@ public final class ComputerSet extends AbstractModelObject {
         app.checkPermission(Hudson.ADMINISTER);  // TODO: new permission?
 
         try {
-            checkName(name);
+            name = checkName(name);
         } catch (ParseException e) {
             rsp.setStatus(SC_BAD_REQUEST);
             sendError(e,req,rsp);
@@ -275,8 +275,9 @@ public final class ComputerSet extends AbstractModelObject {
 
     /**
      * Makes sure that the given name is good as a slave name.
+     * @return trimmed name if valid; throws ParseException if not
      */
-    private void checkName(String name) throws ParseException {
+    private String checkName(String name) throws ParseException {
         if(name==null)
             throw new ParseException("Query parameter 'name' is required",0);
 
@@ -287,6 +288,7 @@ public final class ComputerSet extends AbstractModelObject {
             throw new ParseException(Messages.ComputerSet_SlaveAlreadyExists(name),0);
 
         // looks good
+        return name;
     }
 
     /**
diff --git a/core/src/main/java/hudson/model/Hudson.java b/core/src/main/java/hudson/model/Hudson.java
index 836388de9e2e476f5b579bdf4e2d4915bc04f48f..0229fc0b64242fe49bce9ac1b2bd5b0b07704b37 100644
--- a/core/src/main/java/hudson/model/Hudson.java
+++ b/core/src/main/java/hudson/model/Hudson.java
@@ -2388,23 +2388,16 @@ public final class Hudson extends Node implements ItemGroup<TopLevelItem>, Stapl
             rsp.sendError(HttpServletResponse.SC_BAD_REQUEST,"Query parameter 'name' is required");
             return null;
         }
-        name = name.trim();
-        String mode = req.getParameter("mode");
 
         try {
-            checkGoodName(name);
+            name = checkJobName(name);
         } catch (ParseException e) {
             rsp.setStatus(SC_BAD_REQUEST);
             sendError(e,req,rsp);
             return null;
         }
 
-        if(getItem(name)!=null) {
-            rsp.setStatus(SC_BAD_REQUEST);
-            sendError(Messages.Hudson_JobAlreadyExists(name),req,rsp);
-            return null;
-        }
-
+        String mode = req.getParameter("mode");
         if(mode!=null && mode.equals("copy")) {
             String from = req.getParameter("from");
             TopLevelItem src = getItem(from);
@@ -2535,6 +2528,19 @@ public final class Hudson extends Node implements ItemGroup<TopLevelItem>, Stapl
         // looks good
     }
 
+    /**
+     * Makes sure that the given name is good as a job name.
+     * @return trimmed name if valid; throws ParseException if not
+     */
+    private String checkJobName(String name) throws ParseException {
+        checkGoodName(name);
+        name = name.trim();
+        if(getItem(name)!=null)
+            throw new ParseException(Messages.Hudson_JobAlreadyExists(name),0);
+        // looks good
+        return name;
+    }
+
     private static String toPrintableName(String name) {
         StringBuilder printableName = new StringBuilder();
         for( int i=0; i<name.length(); i++ ) {
@@ -2928,21 +2934,22 @@ public final class Hudson extends Node implements ItemGroup<TopLevelItem>, Stapl
     }
 
     /**
-     * Checks if the top-level item with the given name exists.
+     * Makes sure that the given name is good as a job name.
      */
-    public FormValidation doItemExistsCheck(@QueryParameter String value) {
+    public FormValidation doCheckJobName(@QueryParameter String value) {
         // this method can be used to check if a file exists anywhere in the file system,
         // so it should be protected.
         checkPermission(Item.CREATE);
         
-        String job = fixEmpty(value);
-        if(job==null)
+        if(fixEmpty(value)==null)
             return FormValidation.ok();
 
-        if(getItem(job)==null)
+        try {
+            checkJobName(value);
             return FormValidation.ok();
-        else
-            return FormValidation.error(Messages.Hudson_JobAlreadyExists(job));
+        } catch (ParseException e) {
+            return FormValidation.error(e.getMessage());
+        }
     }
 
     /**
diff --git a/core/src/main/resources/hudson/model/View/newJob.jelly b/core/src/main/resources/hudson/model/View/newJob.jelly
index de0ba223feb53501d8fc01ae639f927f69764818..a90be1a6898069d4c1c96a62c320b9a74de915a6 100644
--- a/core/src/main/resources/hudson/model/View/newJob.jelly
+++ b/core/src/main/resources/hudson/model/View/newJob.jelly
@@ -32,7 +32,7 @@ THE SOFTWARE.
     <l:main-panel>
       <j:getStatic var="jobs" className="hudson.model.Items" field="LIST" />
       <n:form nameTitle="${%Job name}" copyTitle="${%Copy existing job}" copyNames="${app.topLevelItemNames}"
-              descriptors="${jobs}" checkUrl="itemExistsCheck" xmlns:n="/lib/hudson/newFromList" />
+              descriptors="${jobs}" checkUrl="checkJobName" xmlns:n="/lib/hudson/newFromList" />
     </l:main-panel>
   </l:layout>
 </j:jelly>