diff --git a/radioactivity.module b/radioactivity.module
index da9512e..aa2e38a 100644
--- a/radioactivity.module
+++ b/radioactivity.module
@@ -290,15 +290,13 @@ function radioactivity_cron() {
     }
   }
 
-  $last_cron_timestamp = variable_get('radioactivity_last_cron_timestamp', time());
+  $last_cron_timestamp = variable_get('radioactivity_last_cron_timestamp', REQUEST_TIME);
 
   while ($cfg = $configs->fetchObject()) {
 
     // Grab the fields that are of type Radioactivity
     $fields = db_select("field_config_instance", "fci")->fields("fci", array("field_name", "entity_type", "bundle"))->condition("fci.deleted", "0")->condition("fci.field_id", $cfg->id)->execute();
 
-    $time_now = time();
-
     while ($row = $fields->fetchObject()) {
 
       $profile = radioactivity_get_field_profile($row->entity_type, $row->bundle, $row->field_name);
@@ -320,7 +318,7 @@ function radioactivity_cron() {
 
       // Check granularity
       $threshold_timestamp = $last_cron_timestamp - ($last_cron_timestamp % $profile->granularity) + $profile->granularity;
-      if ($time_now < $threshold_timestamp) {
+      if (REQUEST_TIME < $threshold_timestamp) {
         continue;
       }
 
@@ -337,7 +335,7 @@ function radioactivity_cron() {
       // grab update value from deferred values table
       // and update it to the fields table if it is used
       if ($profile->enable_decay == 1) {
-        $updated = db_update($table_name)->expression($energy, $energy . ' * pow(2, (' . $timestamp . ' * 1.0 - ' . $time_now . ') / ' . $half_life . ')')->fields(array($timestamp => $time_now))->condition($timestamp, $time_now, '<')->condition("deleted", "0")->execute();
+        $updated = db_update($table_name)->expression($energy, $energy . ' * pow(2, (' . $timestamp . ' * 1.0 - ' . REQUEST_TIME . ') / ' . $half_life . ')')->fields(array($timestamp => REQUEST_TIME))->condition($timestamp, REQUEST_TIME, '<')->condition("deleted", "0")->execute();
 
         if (module_exists('rules')) {
           // Invoke rules event for cut off
@@ -364,12 +362,12 @@ function radioactivity_cron() {
   $timeout2 = variable_get('radioactivity_flood_timeout', 15) * 120;
 
   // Groom the flood cache
-  db_delete('radioactivity_flood_map')->condition('time', $time_now - $timeout2, "<")->execute();
+  db_delete('radioactivity_flood_map')->condition('time', REQUEST_TIME - $timeout2, "<")->execute();
 
   // clear field caches just to be sure
   field_cache_clear();
 
-  variable_set('radioactivity_last_cron_timestamp', $time_now);
+  variable_set('radioactivity_last_cron_timestamp', REQUEST_TIME);
 
 }