diff --git a/src/calibre/gui2/library/delegates.py b/src/calibre/gui2/library/delegates.py
index 73d722e485..bb73a55fc9 100644
--- a/src/calibre/gui2/library/delegates.py
+++ b/src/calibre/gui2/library/delegates.py
@@ -269,10 +269,11 @@ class CcEnumDelegate(QStyledItemDelegate): # {{{
 
     def setModelData(self, editor, model, index):
         val = unicode(editor.currentText())
-        if val == '':
+        m = index.model()
+        col = m.column_map[index.column()]
+        if val not in m.custom_columns[col]['display']['enum_values']:
             # This shouldn't happen ...
-            m = index.model()
-            col = m.column_map[index.column()]
+            print 'shouldnt happen'
             val = m.custom_columns[col]['display']['enum_values'][0]
         model.setData(index, QVariant(val), Qt.EditRole)
 
diff --git a/src/calibre/gui2/library/models.py b/src/calibre/gui2/library/models.py
index 99639ed0a7..bee90fc44c 100644
--- a/src/calibre/gui2/library/models.py
+++ b/src/calibre/gui2/library/models.py
@@ -719,10 +719,12 @@ class BooksModel(QAbstractTableModel): # {{{
         typ = cc['datatype']
         label=self.db.field_metadata.key_to_label(colhead)
         s_index = None
-        if typ in ('text', 'comments', 'enumeration'):
+        if typ in ('text', 'comments'):
             val = unicode(value.toString()).strip()
             val = val if val else None
-        if typ == 'bool':
+        elif typ == 'enumeration':
+            val = unicode(value.toString()).strip()
+        elif typ == 'bool':
             val = value.toPyObject()
         elif typ == 'rating':
             val = value.toInt()[0]
diff --git a/src/calibre/gui2/preferences/create_custom_column.py b/src/calibre/gui2/preferences/create_custom_column.py
index 47fcb58afb..419fed046d 100644
--- a/src/calibre/gui2/preferences/create_custom_column.py
+++ b/src/calibre/gui2/preferences/create_custom_column.py
@@ -166,8 +166,12 @@ class CreateCustomColumn(QDialog, Ui_QCreateCustomColumn):
             if not self.enum_box.text():
                 return self.simple_error('', _('You must enter at least one'
                     ' value for enumeration columns'))
-            display_dict = {'enum_values':
-                [v.strip() for v in unicode(self.enum_box.text()).split(',')]}
+            l = [v.strip() for v in unicode(self.enum_box.text()).split(',')]
+            for i in range(0, len(l)-1):
+                if l[i] in l[i+1:]:
+                    return self.simple_error('', _('The value "{0}" is in the '
+                    'list more than once').format(l[i]))
+            display_dict = {'enum_values': l}
 
         db = self.parent.gui.library_view.model().db
         key = db.field_metadata.custom_field_prefix+col
diff --git a/src/calibre/gui2/preferences/create_custom_column.ui b/src/calibre/gui2/preferences/create_custom_column.ui
index 54003cd770..360c1a4345 100644
--- a/src/calibre/gui2/preferences/create_custom_column.ui
+++ b/src/calibre/gui2/preferences/create_custom_column.ui
@@ -212,7 +212,10 @@
          <item>
           <widget class="QLineEdit" name="enum_box">
            <property name="toolTip">
-            <string>A comma-separated list of permitted values. The first value is the default</string>
+            <string>A comma-separated list of permitted values. You can specify
+empty values by entering only the comma. For example, the list
+',one,two,three' has 4 valid values, one of them empty. The first
+value in the list is the default.</string>
            </property>
            <property name="sizePolicy">
             <sizepolicy hsizetype="Maximum" vsizetype="Fixed">
diff --git a/src/calibre/library/cli.py b/src/calibre/library/cli.py
index 5049476226..01e8ad449b 100644
--- a/src/calibre/library/cli.py
+++ b/src/calibre/library/cli.py
@@ -580,7 +580,6 @@ def command_add_custom_column(args, dbpath):
         print
         print >>sys.stderr, _('You must specify label, name and datatype')
         return 1
-    print opts.display
     do_add_custom_column(get_db(dbpath, opts), args[0], args[1], args[2],
             opts.is_multiple, json.loads(opts.display))
     # Re-open the DB so that  field_metadata is reflects the column changes