Index: lib/Doctrine/Query/Abstract.php
===================================================================
--- lib/Doctrine/Query/Abstract.php	(revision 7676)
+++ lib/Doctrine/Query/Abstract.php	(working copy)
@@ -1359,9 +1359,11 @@
      */
     public function andWhereIn($expr, $params = array(), $not = false)
     {
-        // if there's no params, return (else we'll get a WHERE IN (), invalid SQL)
-        if (isset($params) and (count($params) == 0)) {
-            return $this;
+        $params = (array) $params;
+
+        // if there's no params, throw exception (else we'll get a WHERE IN (), invalid SQL)
+        if (count($params) == 0) {
+            throw new Doctrine_Query_Exception('You must pass at least one parameter when using an IN() condition.');
         }
 
         if ($this->_hasDqlQueryPart('where')) {
@@ -1386,9 +1388,11 @@
      */
     public function orWhereIn($expr, $params = array(), $not = false)
     {
-        // if there's no params, return (else we'll get a WHERE IN (), invalid SQL)
-        if (isset($params) and (count($params) == 0)) {
-            return $this;
+        $params = (array) $params;
+
+        // if there's no params, throw exception (else we'll get a WHERE IN (), invalid SQL)
+        if (count($params) == 0) {
+            throw new Doctrine_Query_Exception('You must pass at least one parameter when using an IN() condition.');
         }
 
         if ($this->_hasDqlQueryPart('where')) {
@@ -1405,7 +1409,7 @@
     {
         $params = (array) $params;
 
-        // if there's no params, return (else we'll get a WHERE IN (), invalid SQL)
+        // if there's no params, throw exception (else we'll get a WHERE IN (), invalid SQL)
         if (count($params) == 0) {
             throw new Doctrine_Query_Exception('You must pass at least one parameter when using an IN() condition.');
         }