diff --git a/src/ApiConnectors/BrowseDataApiConnector.php b/src/ApiConnectors/BrowseDataApiConnector.php
index 2fa2d9b0..abfac08d 100644
--- a/src/ApiConnectors/BrowseDataApiConnector.php
+++ b/src/ApiConnectors/BrowseDataApiConnector.php
@@ -69,8 +69,10 @@ public function getBrowseData(string $code, array $columns, array $sortFields =
     {
         Assert::minCount($columns, 1);
         Assert::allIsInstanceOf($columns, BrowseColumn::class);
-        Assert::allIsInstanceOf($sortFields, BrowseSortField::class);
-
+        if(count($sortFields)) {
+            Assert::allIsInstanceOf($sortFields, BrowseSortField::class);
+        }
+        
         $requestBrowseData = new BrowseData($code, $columns, $sortFields);
 
         $response = $this->sendXmlDocument($requestBrowseData);
diff --git a/src/BrowseDataRow.php b/src/BrowseDataRow.php
index 4ae7f1b8..b49ae1a8 100644
--- a/src/BrowseDataRow.php
+++ b/src/BrowseDataRow.php
@@ -54,10 +54,10 @@ public function getCode(): string
     }
 
     /**
-     * @param string $code
+     * @param string|null $code
      * @return BrowseDataRow
      */
-    public function setCode(string $code): BrowseDataRow
+    public function setCode(?string $code): BrowseDataRow
     {
         $this->code = $code;
         return $this;
@@ -72,10 +72,10 @@ public function getNumber(): int
     }
 
     /**
-     * @param int $number
+     * @param int|null $number
      * @return BrowseDataRow
      */
-    public function setNumber(int $number): BrowseDataRow
+    public function setNumber(?int $number): BrowseDataRow
     {
         $this->number = $number;
         return $this;
@@ -90,10 +90,10 @@ public function getLine(): int
     }
 
     /**
-     * @param int $line
+     * @param int|null $line
      * @return BrowseDataRow
      */
-    public function setLine(int $line): BrowseDataRow
+    public function setLine(?int $line): BrowseDataRow
     {
         $this->line = $line;
         return $this;
diff --git a/src/Request/BrowseData.php b/src/Request/BrowseData.php
index 76aed249..cfefa7ca 100644
--- a/src/Request/BrowseData.php
+++ b/src/Request/BrowseData.php
@@ -39,7 +39,9 @@ public function __construct(string $code, array $columns, array $sortFields = []
         parent::__construct();
 
         Assert::allIsInstanceOf($columns, BrowseColumn::class);
-        Assert::allIsInstanceOf($sortFields, BrowseSortField::class);
+        if(count($sortFields)) {
+            Assert::allIsInstanceOf($sortFields, BrowseSortField::class);
+        }
 
         $this->columnsElement = $this->createElement('columns');
         $this->columnsElement->setAttribute('code', $code);
@@ -48,7 +50,9 @@ public function __construct(string $code, array $columns, array $sortFields = []
         $this->columnsElement->appendChild($this->sortElement);
 
         $this->addColumns($columns);
-        $this->addSortFields($sortFields);
+        if(count($sortFields)) {
+            $this->addSortFields($sortFields);
+        }
 
         $this->appendChild($this->columnsElement);
     }