diff --git a/lib/OpenLayers/Util.js b/lib/OpenLayers/Util.js
index 491448c9c9..cfa5ce2517 100644
--- a/lib/OpenLayers/Util.js
+++ b/lib/OpenLayers/Util.js
@@ -139,7 +139,8 @@ OpenLayers.Util.indexOf = function(array, obj) {
  *
  * Parameters:
  * element - {DOMElement} DOM element to modify.
- * id - {String} The element id attribute to set.
+ * id - {String} The element id attribute to set.  Note that dots (".") will be
+ *     replaced with underscore ("_") in setting the element id.
  * px - {<OpenLayers.Pixel>|Object} The element left and top position,
  *                                  OpenLayers.Pixel or an object with
  *                                  a 'x' and 'y' properties.
@@ -157,7 +158,7 @@ OpenLayers.Util.modifyDOMElement = function(element, id, px, sz, position,
                                             border, overflow, opacity) {
 
     if (id) {
-        element.id = id;
+        element.id = id.replace(/\./g, "_");
     }
     if (px) {
         element.style.left = px.x + "px";
@@ -195,7 +196,8 @@ OpenLayers.Util.modifyDOMElement = function(element, id, px, sz, position,
  * Parameters:
  * id - {String} An identifier for this element.  If no id is
  *               passed an identifier will be created 
- *               automatically.
+ *               automatically.  Note that dots (".") will be replaced with
+ *               underscore ("_") when generating ids.
  * px - {<OpenLayers.Pixel>|Object} The element left and top position,
  *                                  OpenLayers.Pixel or an object with
  *                                  a 'x' and 'y' properties.
@@ -928,6 +930,7 @@ OpenLayers.Util.lastSeqID = 0;
  * 
  * Parameters:
  * prefix - {String} Optional string to prefix unique id. Default is "id_".
+ *     Note that dots (".") in the prefix will be replaced with underscore ("_").
  * 
  * Returns:
  * {String} A unique id string, built on the passed in prefix.
@@ -935,6 +938,8 @@ OpenLayers.Util.lastSeqID = 0;
 OpenLayers.Util.createUniqueID = function(prefix) {
     if (prefix == null) {
         prefix = "id_";
+    } else {
+        prefix = prefix.replace(/\./g, "_");
     }
     OpenLayers.Util.lastSeqID += 1; 
     return prefix + OpenLayers.Util.lastSeqID;        
diff --git a/tests/Feature.html b/tests/Feature.html
index 4a50d5143a..aa3db24a3d 100644
--- a/tests/Feature.html
+++ b/tests/Feature.html
@@ -21,7 +21,7 @@
 
         t.ok( feature instanceof OpenLayers.Feature, "new OpenLayers.Feature returns Feature object" );
         t.eq( feature.layer, layer, "feature.layer set correctly" );
-        t.ok(OpenLayers.String.startsWith(feature.id, "OpenLayers.Feature_"),
+        t.ok(OpenLayers.String.startsWith(feature.id, "OpenLayers_Feature_"),
              "feature.id set correctly");
         t.ok( feature.lonlat.equals(lonlat), "feature.lonlat set correctly" );
         t.eq( feature.data.iconURL, iconURL, "feature.data.iconURL set correctly" );
diff --git a/tests/Geometry.html b/tests/Geometry.html
index e61326d34f..6bae0ca16f 100644
--- a/tests/Geometry.html
+++ b/tests/Geometry.html
@@ -11,7 +11,7 @@
         var g = new OpenLayers.Geometry();
         
         t.eq(g.CLASS_NAME, "OpenLayers.Geometry", "correct CLASS_NAME")
-        t.ok(OpenLayers.String.startsWith(g.id, "OpenLayers.Geometry_"),
+        t.ok(OpenLayers.String.startsWith(g.id, "OpenLayers_Geometry_"),
              "id correctly set");
     }
 
@@ -22,7 +22,7 @@
         var clone = geometry.clone();
 
         t.eq(clone.CLASS_NAME, "OpenLayers.Geometry", "correct CLASS_NAME")
-        t.ok(OpenLayers.String.startsWith(clone.id, "OpenLayers.Geometry_"),
+        t.ok(OpenLayers.String.startsWith(clone.id, "OpenLayers_Geometry_"),
              "id correctly set");
     }
 
diff --git a/tests/Popup.html b/tests/Popup.html
index 2d6a90b98e..766ac59e0d 100644
--- a/tests/Popup.html
+++ b/tests/Popup.html
@@ -13,7 +13,7 @@
         popup = new OpenLayers.Popup();
 
         t.ok( popup instanceof OpenLayers.Popup, "new OpenLayers.Popup returns Popup object" );
-        t.ok(OpenLayers.String.startsWith(popup.id, "OpenLayers.Popup"),
+        t.ok(OpenLayers.String.startsWith(popup.id, "OpenLayers_Popup"),
              "valid default popupid");
         var firstID = popup.id;
         t.ok(popup.contentSize.equals(size), "good default popup.size");
diff --git a/tests/Popup/Anchored.html b/tests/Popup/Anchored.html
index f53546b0c0..3197e84655 100644
--- a/tests/Popup/Anchored.html
+++ b/tests/Popup/Anchored.html
@@ -11,7 +11,7 @@
         popup = new OpenLayers.Popup.Anchored();
 
         t.ok( popup instanceof OpenLayers.Popup.Anchored, "new OpenLayers.Popup.Anchored returns Popup.Anchored object" );
-        t.ok(OpenLayers.String.startsWith(popup.id, "OpenLayers.Popup.Anchored"), "valid default popupid");
+        t.ok(OpenLayers.String.startsWith(popup.id, "OpenLayers_Popup_Anchored"), "valid default popupid");
         var firstID = popup.id;
         t.eq(popup.contentHTML, null, "good default popup.contentHTML");