diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 15729e89fe..46baf3cff5 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -3776,7 +3776,7 @@ function _drupal_shutdown_function() {
   chdir(DRUPAL_ROOT);
 
   try {
-    foreach ($callbacks as $key => $callback) {
+    foreach ($callbacks as $callback) {
       call_user_func_array($callback['callback'], $callback['arguments']);
     }
   }
diff --git a/includes/install.inc b/includes/install.inc
index 08518fed08..b7db783586 100644
--- a/includes/install.inc
+++ b/includes/install.inc
@@ -779,7 +779,7 @@ function drupal_uninstall_modules($module_list = array(), $uninstall_dependents
     $module_list = array_flip(array_values($module_list));
 
     $profile = drupal_get_profile();
-    foreach ($module_list as $module => $weight) {
+    foreach (array_keys($module_list) as $module) {
       if (!isset($module_data[$module]) || drupal_get_installed_schema_version($module) == SCHEMA_UNINSTALLED) {
         // This module doesn't exist or is already uninstalled. Skip it.
         unset($module_list[$module]);
diff --git a/includes/menu.inc b/includes/menu.inc
index d32c6ac6d4..9bee2216c7 100644
--- a/includes/menu.inc
+++ b/includes/menu.inc
@@ -2403,7 +2403,6 @@ function menu_set_active_trail($new_trail = NULL) {
       // a stripped down menu tree containing the active trail only, in case
       // the given menu has not been built in this request yet.
       $tree = menu_tree_page_data($preferred_link['menu_name'], NULL, TRUE);
-      $key = key($tree);
       $curr = current($tree);
     }
     // There is no link for the current path.
@@ -2434,7 +2433,6 @@ function menu_set_active_trail($new_trail = NULL) {
         }
         $tree = $curr['below'] ? $curr['below'] : array();
       }
-      $key = key($tree);
       $curr = current($tree);
       next($tree);
     }
diff --git a/includes/module.inc b/includes/module.inc
index 54205f5348..f8e229dd78 100644
--- a/includes/module.inc
+++ b/includes/module.inc
@@ -404,7 +404,7 @@ function module_enable($module_list, $enable_dependencies = TRUE) {
     // Create an associative array with weights as values.
     $module_list = array_flip(array_values($module_list));
 
-    foreach ($module_list as $module => $weight) {
+    while ($module = key($module_list)) {
       if (!isset($module_data[$module])) {
         // This module is not found in the filesystem, abort.
         return FALSE;
@@ -423,6 +423,8 @@ function module_enable($module_list, $enable_dependencies = TRUE) {
           $module_list[$dependency] = 0;
         }
       }
+
+      next($module_list);
     }
 
     if (!$module_list) {
@@ -540,7 +542,7 @@ function module_disable($module_list, $disable_dependents = TRUE) {
     $module_list = array_flip(array_values($module_list));
 
     $profile = drupal_get_profile();
-    foreach ($module_list as $module => $weight) {
+    while ($module = key($module_list)) {
       if (!isset($module_data[$module]) || !$module_data[$module]->status) {
         // This module doesn't exist or is already disabled, skip it.
         unset($module_list[$module]);
@@ -555,6 +557,8 @@ function module_disable($module_list, $disable_dependents = TRUE) {
           $module_list[$dependent] = 0;
         }
       }
+
+      next($module_list);
     }
 
     // Sort the module list by pre-calculated weights.