diff --git a/CHANGELOG b/CHANGELOG
index bd3bcf3..902b545 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Escape ":" and "." characters when doing contextual CSS selection in browsers that support querySelectorAll. [#559 state:resolved] (fxtentacle, Andrew Dupont)
+
 * Ensure the `target` property on events is never undefined in IE. [#383 state:resolved] (Mathias Karstädt, Diego Perini, Andrew Dupont)
 
 * Ensure Element#descendants always returns an array. [#373 state:resolved] (kangax)
diff --git a/src/dom/selector.js b/src/dom/selector.js
index 979b7fe..331299d 100644
--- a/src/dom/selector.js
+++ b/src/dom/selector.js
@@ -122,9 +122,11 @@ var Selector = Class.create({
         // Add an explicit context to the selector if necessary.
         if (root !== document) {
           var oldId = root.id, id = $(root).identify();
+          // Escape special characters in the ID.
+          id = id.replace(/[\.:]/g, "\\$0");
           e = "#" + id + " " + e;
         }
-
+        
         results = $A(root.querySelectorAll(e)).map(Element.extend);
         root.id = oldId;