Index: core/kernel/utility/validator.php
===================================================================
--- core/kernel/utility/validator.php
+++ core/kernel/utility/validator.php
@@ -228,8 +228,12 @@
 	{
 		$res = true;
 		$val = $this->dataSource->GetDBField($field);
+		$value_length = is_scalar($val) ? mb_strlen($val) : 0;
 
-		if ( isset($params['type']) && preg_match("#int|integer|double|float|real#", $params['type']) && strlen($val) > 0 ) {
+		if ( isset($params['type'])
+			&& preg_match('#int|integer|double|float|real#', $params['type'])
+			&& $value_length > 0
+		) {
 			// validate number
 			if ( isset($params['max_value_inc'])) {
 				$res = $res && $val <= $params['max_value_inc'];
@@ -264,14 +268,14 @@
 			return false;
 		}
 
-		if ( strlen($val) > 0 ) {
+		if ( $value_length > 0 ) {
 			// Validate string.
 			if ( isset($params['max_len']) ) {
-				$res = $res && mb_strlen($val) <= $params['max_len'];
+				$res = $res && $value_length <= $params['max_len'];
 			}
 
 			if ( isset($params['min_len']) ) {
-				$res = $res && mb_strlen($val) >= $params['min_len'];
+				$res = $res && $value_length >= $params['min_len'];
 			}
 		}
 
@@ -279,7 +283,7 @@
 			$error_params = array(
 				'min_length' => (int)getArrayValue($params, 'min_len'),
 				'max_length' => (int)getArrayValue($params, 'max_len'),
-				'value' => mb_strlen($val)
+				'value' => $value_length,
 			);
 			$this->SetError($field, 'length_out_of_range', null, $error_params);