diff --git a/app/views/custom_fields/_form.rhtml b/app/views/custom_fields/_form.rhtml
index 874c571bf..d26af9420 100644
--- a/app/views/custom_fields/_form.rhtml
+++ b/app/views/custom_fields/_form.rhtml
@@ -54,7 +54,8 @@ function toggle_custom_field_format() {
 
 <div class="box">
 <p><%= f.text_field :name, :required => true %></p>
-<p><%= f.select :field_format, custom_field_formats_for_select, {}, :onchange => "toggle_custom_field_format();" %></p>
+<p><%= f.select :field_format, custom_field_formats_for_select, {}, :onchange => "toggle_custom_field_format();",
+																																		:disabled => !@custom_field.new_record? %></p>
 <p><label for="custom_field_min_length"><%=l(:label_min_max_length)%></label>
    <%= f.text_field :min_length, :size => 5, :no_label => true %> - 
    <%= f.text_field :max_length, :size => 5, :no_label => true %><br>(<%=l(:text_min_max_length_info)%>)</p>