diff --git uc_dependent_attributes.module uc_dependent_attributes.module
index 394ba04..9903269 100644
--- uc_dependent_attributes.module
+++ uc_dependent_attributes.module
@@ -63,7 +63,7 @@ function uc_dependent_attributes_form_alter(&$form, $form_state, $form_id) {
       }
   
       // Build a hierarchy array of all possible attribute option combinations
-      $possible = array_hierarchy($possible);
+      $possible = uc_dependent_attributes_array_hierarchy($possible);
   
       $disabled = array();
       // Retrieve all disabled attribute option combinations
@@ -86,11 +86,11 @@ function uc_dependent_attributes_form_alter(&$form, $form_state, $form_id) {
         }
   
         // Build an array hierarchy and merge with other combos
-        $disabled = array_merge_recursive_preserve($disabled, array_hierarchy($combo_ordered));
+        $disabled = uc_dependent_attributes_array_merge_recursive_preserve($disabled, uc_dependent_attributes_array_hierarchy($combo_ordered));
       }
   
       // Filter out all disabled combinations from the possible combinations
-      $filtered = array_diff_assoc_recursive($possible, $disabled);
+      $filtered = uc_dependent_attributes_array_diff_assoc_recursive($possible, $disabled);
   
       // Update the form attributes
       _uc_dependent_attributes_filter($filtered, $_POST['attributes'], $form['#parameters'][2]->attributes);
@@ -171,7 +171,7 @@ function _uc_dependent_attributes_filter($combos, &$selected, &$attributes) {
  * @return array
  *   Returns a hierarchy array of the 2-dimensional array.
  */
-function array_hierarchy($array) {
+function uc_dependent_attributes_array_hierarchy($array) {
   // Get the first element from the array
   $return = array_slice($array, 0, 1, true);
   // Remove the first element from the array
@@ -179,8 +179,8 @@ function array_hierarchy($array) {
 
   // If the array is not empty
   if (!empty($array)) {
-    // Recursivley call the array_hierarchy function
-    $child = array_hierarchy($array);
+    // Recursivley call the uc_dependent_attributes_array_hierarchy function
+    $child = uc_dependent_attributes_array_hierarchy($array);
     // Add the child to all parent elements
     foreach ($return as $pkey => $pvalue) {
       foreach ($pvalue as $ckey => $cvalue) {
@@ -200,7 +200,7 @@ function array_hierarchy($array) {
  *   Returns an array containg all merged keys => values from all passed in
  *   arrays.
  */
-function array_merge_recursive_preserve() {
+function uc_dependent_attribute_array_merge_recursive_preserve() {
   // Holds all the arrays passed
   $params = &func_get_args();
 
@@ -213,7 +213,7 @@ function array_merge_recursive_preserve() {
       // Numeric keyed values are added (unless already there)
       if (is_numeric($key)) {
         if (is_array($value) && !empty($value)) {
-          $return[$key] = array_merge_recursive_preserve($return[$key], $value);
+          $return[$key] = uc_dependent_attributes_array_merge_recursive_preserve($return[$key], $value);
         }
         else {
           $return[$key] = $value;
@@ -222,7 +222,7 @@ function array_merge_recursive_preserve() {
       // String keyed values are replaced
       else {
         if (isset($return[$key]) && is_array($value) && is_array($return[$key])) {
-          $return[$key] = array_merge_recursive_preserve($return[$key], $value);
+          $return[$key] = uc_dependent_attributes_array_merge_recursive_preserve($return[$key], $value);
         }
         else {
           $return[$key] = $value;
@@ -241,7 +241,7 @@ function array_merge_recursive_preserve() {
  *   Returns an array containg all the values from the first array that are not
  *   present in any subsequent array.
  */
-function array_diff_assoc_recursive() {
+function uc_dependent_attributes_array_diff_assoc_recursive() {
   // Holds all the arrays passed
   $params = &func_get_args();
 
@@ -254,7 +254,7 @@ function array_diff_assoc_recursive() {
         $diff[$key] = $value;
       }
       else {
-        $new = array_diff_assoc_recursive($value, $params[0][$key]);
+        $new = uc_dependent_attributes_array_diff_assoc_recursive($value, $params[0][$key]);
         if ($new != false) {
           $diff[$key] = $new;
         }