diff --git a/core/oql/expression.class.inc.php b/core/oql/expression.class.inc.php
index dd3a73192..2cea667be 100644
--- a/core/oql/expression.class.inc.php
+++ b/core/oql/expression.class.inc.php
@@ -960,6 +960,7 @@ class FieldExpression extends UnaryExpression
 	 */
 	public function GetCriterion($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
 	{
+		$oAttDef = $this->GetAttDef($oSearch->GetJoinedClasses());
 		if (!is_null($oAttDef))
 		{
 			$sSearchType = $oAttDef->GetSearchType();
@@ -968,7 +969,6 @@ class FieldExpression extends UnaryExpression
 		{
 			$sSearchType = AttributeDefinition::SEARCH_WIDGET_TYPE;
 		}
-
 		return array(
 			'widget' => $sSearchType,
 			'ref' => $this->GetParent().'.'.$this->GetName(),
@@ -1532,25 +1532,35 @@ class FunctionExpression extends Expression
 
 	public function GetCriterion($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
 	{
-		if ($this->m_sVerb != 'DATE_SUB' && $this->m_sVerb != 'DATE_ADD' && $this->m_sVerb != 'NOW')
+		$aCriteria = array();
+		switch ($this->m_sVerb)
 		{
-			return parent::GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
-		}
+			case 'ISNULL':
+				$aCriteria['operator'] = $this->m_sVerb;
+				foreach($this->m_aArgs as $oExpression)
+				{
+					$aCriteria = array_merge($oExpression->GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef), $aCriteria);
+				}
+				break;
 
-		$aCriteria = array('widget' => 'date_time');
+			case 'NOW':
+				$aCriteria = array('widget' => 'date_time');
+				$aCriteria['is_relative'] = true;
+				$aCriteria['verb'] = $this->m_sVerb;
+				break;
 
-		foreach($this->m_aArgs as $oExpression)
-		{
-			$aCriteria = array_merge($oExpression->GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef), $aCriteria);
-		}
+			case 'DATE_ADD':
+			case 'DATE_SUB':
+				$aCriteria = array('widget' => 'date_time');
+				foreach($this->m_aArgs as $oExpression)
+				{
+					$aCriteria = array_merge($oExpression->GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef), $aCriteria);
+				}
+				$aCriteria['verb'] = $this->m_sVerb;
+				break;
 
-		if ($this->m_sVerb == 'NOW')
-		{
-			$aCriteria['is_relative'] = true;
-		}
-		else
-		{
-			$aCriteria['verb'] = $this->m_sVerb;
+			default:
+				return parent::GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
 		}
 
 		return $aCriteria;
diff --git a/sources/application/search/criterionconversion/criteriontooql.class.inc.php b/sources/application/search/criterionconversion/criteriontooql.class.inc.php
index c4fb75e4c..b341c103d 100644
--- a/sources/application/search/criterionconversion/criteriontooql.class.inc.php
+++ b/sources/application/search/criterionconversion/criteriontooql.class.inc.php
@@ -122,6 +122,10 @@ class CriterionToOQL extends CriterionConversionAbstract
 
 	protected static function EmptyToOql($sRef, $aCriteria)
 	{
+		if ($aCriteria['widget'] == AttributeDefinition::SEARCH_WIDGET_TYPE_NUMERIC)
+		{
+			return "ISNULL({$sRef})";
+		}
 		return "({$sRef} = '')";
 	}
 
diff --git a/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php b/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php
index 73ff8ffb4..a376eab97 100644
--- a/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php
+++ b/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php
@@ -59,6 +59,7 @@ class CriterionToSearchForm extends CriterionConversionAbstract
 			AttributeDefinition::SEARCH_WIDGET_TYPE_ENUM => 'EnumToSearchForm',
 			AttributeDefinition::SEARCH_WIDGET_TYPE_DATE => 'DateToSearchForm',
 			AttributeDefinition::SEARCH_WIDGET_TYPE_DATE_TIME => 'DateTimeToSearchForm',
+			AttributeDefinition::SEARCH_WIDGET_TYPE_NUMERIC => 'NumericToSearchForm',
 		);
 
 		foreach($aAndCriterionRaw as $aCriteria)
@@ -374,4 +375,16 @@ class CriterionToSearchForm extends CriterionConversionAbstract
 
 		return $aCriteria;
 	}
+
+	protected static function NumericToSearchForm($aCriteria, $aFields)
+	{
+		if ($aCriteria['operator'] == 'ISNULL')
+		{
+			$aCriteria['operator'] = CriterionConversionAbstract::OP_EMPTY;
+		}
+
+		return $aCriteria;
+	}
+
+
 }
\ No newline at end of file
diff --git a/test/application/search/CriterionConversionTest.php b/test/application/search/CriterionConversionTest.php
index e0d20636a..8c77d32c3 100644
--- a/test/application/search/CriterionConversionTest.php
+++ b/test/application/search/CriterionConversionTest.php
@@ -339,6 +339,7 @@ class CriterionConversionTest extends ItopDataTestCase
 	function OqlProvider()
 	{
 		return array(
+			array('OQL' => "SELECT Server WHERE ISNULL(nb_u)"),
 			array('OQL' => "SELECT Contact WHERE status = 'active'"),
 			array('OQL' => "SELECT Contact WHERE status = 'active' AND name LIKE 'toto%'"),
 			array('OQL' => "SELECT Contact WHERE status = 'active' AND org_id = 3"),
@@ -350,6 +351,7 @@ class CriterionConversionTest extends ItopDataTestCase
 			array('OQL' => "SELECT UserRequest WHERE start_date >= '2017-01-01 00:00:00' AND '2017-01-01 00:00:00' >= start_date"),
 			array('OQL' => "SELECT UserRequest WHERE start_date >= '2017-01-01 00:00:00' AND '2017-01-01 01:00:00' > start_date"),
 			array('OQL' => "SELECT UserRequest WHERE start_date >= '2017-01-01 00:00:00' AND '2017-01-02 00:00:00' > start_date"),
+
 		);
 	}
 }