diff --git a/internal.inc.php b/internal.inc.php
index d3bcfa6..8c5bb64 100644
--- a/internal.inc.php
+++ b/internal.inc.php
@@ -97,8 +97,6 @@ function _get_task_candidates()
   //get tasks defined as closures
   foreach($TASKMAN_CLOSURES as $name => $args)
   {
-    if(isset($cands[$name]))
-      throw new Exception("Task '$name' is already defined");
     $cands[$name] = $args;
   }
 
diff --git a/util.inc.php b/util.inc.php
index dca1f89..f880366 100644
--- a/util.inc.php
+++ b/util.inc.php
@@ -74,6 +74,9 @@ function task($name)
 {
   global $TASKMAN_CLOSURES;
 
+  if(isset($TASKMAN_CLOSURES[$name]))
+    throw new TaskmanException("Task '$name' is already defined");
+
   $args = func_get_args();
   $TASKMAN_CLOSURES[$name] = $args; 
 }