diff --git a/CHANGELOG b/CHANGELOG
index 0ca90ad..768b98e 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Don't redeclare previously declared variables. Closes #10007 [kuriyama]
+
 * For consistency: use Object.isUndefined where possible. [Tobie Langel]
 
 * Make String#isJSON return false for empty or blank strings. Make Ajax.Response#responseJSON null when Ajax.Response#responseText is empty or blank. [Andrew Dupont, Thomas Fuchs, Tobie Langel]
diff --git a/src/dom.js b/src/dom.js
index 49cc145..599c8ef 100644
--- a/src/dom.js
+++ b/src/dom.js
@@ -289,7 +289,8 @@ Element.Methods = {
     else attributes[name] = Object.isUndefined(value) ? true : value;
     
     for (var attr in attributes) {
-      var name = t.names[attr] || attr, value = attributes[attr];
+      name = t.names[attr] || attr;
+      value = attributes[attr];
       if (t.values[attr]) name = t.values[attr](element, value);
       if (value === false || value === null)
         element.removeAttribute(name);
@@ -792,7 +793,7 @@ else if (Prototype.Browser.IE) {
           return node ? node.value : "";
         },
         _getEv: function(element, attribute) {
-          var attribute = element.getAttribute(attribute);
+          attribute = element.getAttribute(attribute);
           return attribute ? attribute.toString().slice(23, -2) : null;
         },
         _flag: function(element, attribute) {
diff --git a/src/selector.js b/src/selector.js
index 6b4c8d9..3bc72a7 100644
--- a/src/selector.js
+++ b/src/selector.js
@@ -163,7 +163,7 @@ Object.extend(Selector, {
       'enabled':     "[not(@disabled)]",
       'not': function(m) {
         var e = m[6], p = Selector.patterns,
-            x = Selector.xpath, le, m, v;
+            x = Selector.xpath, le, v;
             
         var exclusion = [];
         while (e && le != e && (/\S/).test(e)) {
@@ -612,7 +612,8 @@ Object.extend(Selector, {
   },
   
   findChildElements: function(element, expressions) {
-    var exprs = expressions.join(','), expressions = [];
+    var exprs = expressions.join(',');
+    expressions = [];
     exprs.scan(/(([\w#:.~>+()\s-]+|\*|\[.*?\])+)\s*(,|$)/, function(m) {
       expressions.push(m[1].strip());
     });
diff --git a/src/string.js b/src/string.js
index 30d0ffb..1fa396e 100644
--- a/src/string.js
+++ b/src/string.js
@@ -247,7 +247,8 @@ var Template = Class.create({
       if (before == '\\') return match[2];
       
       var ctx = object, expr = match[3];
-      var pattern = /^([^.[]+|\[((?:.*?[^\\])?)\])(\.|\[|$)/, match = pattern.exec(expr);
+      var pattern = /^([^.[]+|\[((?:.*?[^\\])?)\])(\.|\[|$)/;
+      match = pattern.exec(expr);
       if (match == null) return before;
 
       while (match != null) {