diff --git a/devel.admin.inc b/devel.admin.inc
index e0b242e..c9ecbc0 100644
--- a/devel.admin.inc
+++ b/devel.admin.inc
@@ -35,6 +35,14 @@ function devel_admin_settings() {
     '#maxlength' => 4,
     '#description' => t('Enter an integer in milliseconds. Any query which takes longer than this many milliseconds will be highlighted in the query log. This indicates a possibly inefficient query, or a candidate for caching.'),
   );
+  $form['queries']['settings']['devel_query_random_range'] = array(
+    '#type' => 'textfield',
+    '#title' => t('Query log clear range'),
+    '#default_value' => variable_get('devel_query_random_range', 1000),
+    '#size' => 4,
+    '#maxlength' => 4,
+    '#description' => t('You may want to decrease this value if you suffer from querylog files accumulation. The lower this value is, the more often querylog directory will be cleaned.'),
+  );
 
   $form['devel_api_url'] = array('#type' => 'textfield',
     '#title' => t('API Site'),
diff --git a/devel.install b/devel.install
index f082857..523df8b 100644
--- a/devel.install
+++ b/devel.install
@@ -52,6 +52,7 @@ function devel_uninstall() {
   variable_del('devel_xhprof_url');
   variable_del('devel_debug_mail_file_format');
   variable_del('devel_debug_mail_directory');
+  variable_del('devel_query_random_range');
 
   // Delete the development menu.
   if (module_exists('menu')) {
diff --git a/devel.module b/devel.module
index f355148..81b5f76 100644
--- a/devel.module
+++ b/devel.module
@@ -1205,7 +1205,9 @@ function devel_query_put_contents($queries) {
   file_prepare_directory($path, FILE_CREATE_DIRECTORY);
 
   // Occassionally wipe the querylog dir so that files don't accumulate.
-  if (mt_rand(1, 1000) == 401) {
+  $range = variable_get('devel_query_random_range', 1000);
+
+  if (mt_rand(1, $range) == intval($range/2)) {
     devel_empty_dir($path);
   }