diff --git a/core/dbobjectsearch.class.php b/core/dbobjectsearch.class.php
index bd461b022..0dba2f23c 100644
--- a/core/dbobjectsearch.class.php
+++ b/core/dbobjectsearch.class.php
@@ -2097,4 +2097,9 @@ class DBObjectSearch extends DBSearch
 		}
 		return $oExpression;
 	}
+
+	public function ListParameters()
+	{
+		return $this->GetCriteria()->ListParameters();
+	}
 }
diff --git a/core/dbsearch.class.php b/core/dbsearch.class.php
index 66884183e..c4e9d6a12 100644
--- a/core/dbsearch.class.php
+++ b/core/dbsearch.class.php
@@ -1230,6 +1230,8 @@ abstract class DBSearch
 	 */
 	public abstract function GetCriteria();
 
+	public abstract function ListParameters();
+
     /**
      * Shortcut to add efficient IN condition
      *
diff --git a/core/dbunionsearch.class.php b/core/dbunionsearch.class.php
index adcd76c51..3d659bbf8 100644
--- a/core/dbunionsearch.class.php
+++ b/core/dbunionsearch.class.php
@@ -728,4 +728,14 @@ class DBUnionSearch extends DBSearch
 			$oSearch->AddConditionExpression($oInCondition);
 		}
 	}
+
+	public function ListParameters()
+	{
+		$aParameters = array();
+		foreach ($this->aSearches as $oSearch)
+		{
+			$aParameters = array_merge($aParameters, $oSearch->ListParameters());
+		}
+		return $aParameters;
+	}
 }
diff --git a/core/oql/expression.class.inc.php b/core/oql/expression.class.inc.php
index 5bce60fb8..8b2e43e27 100644
--- a/core/oql/expression.class.inc.php
+++ b/core/oql/expression.class.inc.php
@@ -2624,7 +2624,7 @@ class IntervalExpression extends Expression
 
 	public function ListParameters()
 	{
-		return array();
+		return $this->m_oValue->ListParameters();
 	}
 
 	public function RenameParam($sOldName, $sNewName)
diff --git a/test/core/ExpressionTest.php b/test/core/ExpressionTest.php
new file mode 100644
index 000000000..2ceef3944
--- /dev/null
+++ b/test/core/ExpressionTest.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace Combodo\iTop\Test\UnitTest\Core;
+
+use Combodo\iTop\Test\UnitTest\ItopDataTestCase;
+use Expression;
+
+class ExpressionTest extends ItopDataTestCase
+{
+	const USE_TRANSACTION = false;
+
+	/**
+	 * @dataProvider ListParametersProvider
+	 * @param $sOQL
+	 * @param $aExpected
+	 *
+	 * @throws \OQLException
+	 */
+	public function testListParameters($sOQL, $aExpected)
+	{
+		$oExpression = Expression::FromOQL($sOQL);
+		$aParameters = $oExpression->ListParameters();
+		$aResult = array();
+		foreach ($aParameters as $oVarExpr)
+		{
+			/** var \VariableExpression $oVarExpr */
+			$aResult[] = $oVarExpr->RenderExpression();
+		}
+		$this->debug($aResult);
+		$this->assertSame(array_diff($aExpected, $aResult), array_diff($aResult, $aExpected));
+	}
+
+	public function ListParametersProvider()
+	{
+		return array(
+			array('1', array()),
+			array(':id = 2', array(':id')),
+			array('expiration_date < DATE_SUB(NOW(), INTERVAL :expiration_days DAY)', array(':expiration_days')),
+			array('id IN (SELECT Organization WHERE :id = 2)', array(':id')),
+			array('id IN (:id, 2)', array(':id')),
+			array("B.name LIKE :name", array(':name')),
+			array("name REGEXP :regexp", array(':regexp')),
+			array(" t.agent_id = :current_contact_id", array(':current_contact_id')),
+			array("INET_ATON(dev.managementip) > INET_ATON('10.22.32.224') AND INET_ATON(:ip) < INET_ATON('10.22.32.255')", array(':ip')),
+		);
+	}
+}
diff --git a/test/core/OQLTest.php b/test/core/OQLTest.php
index e1f74f879..eb7bf7230 100644
--- a/test/core/OQLTest.php
+++ b/test/core/OQLTest.php
@@ -402,6 +402,7 @@ class OQLTest extends ItopDataTestCase
 		}
 		catch (Exception $e)
 		{
+			$this->debug($e->getMessage());
 			$sExceptionClass = get_class($e);
 		}