diff --git a/lib/OpenLayers/Format/SLD/v1.js b/lib/OpenLayers/Format/SLD/v1.js
index 87a7960e3d..f4fcb40f5f 100644
--- a/lib/OpenLayers/Format/SLD/v1.js
+++ b/lib/OpenLayers/Format/SLD/v1.js
@@ -437,6 +437,12 @@ OpenLayers.Format.SLD.v1 = OpenLayers.Class(OpenLayers.Format.Filter.v1_0_0, {
                         "xsi:schemaLocation": this.schemaLocation
                     }}
                 );
+
+                // For ArcGIS Server it is necessary to define this
+                // at the root level (see ticket:2166).
+                root.setAttribute("xmlns:ogc", this.namespaces.ogc);
+                root.setAttribute("xmlns:gml", this.namespaces.gml);
+
                 // add in optional name
                 if(sld.name) {
                     this.writeNode("Name", sld.name, root);