diff --git a/src/BookSearch/BookSearch.php b/src/BookSearch/BookSearch.php
index 51e4d6e..fb75786 100644
--- a/src/BookSearch/BookSearch.php
+++ b/src/BookSearch/BookSearch.php
@@ -289,21 +289,19 @@ class BookSearch
         // in chunks if we are above the limit. 15 was found by testing and seems to be a sweet spot
         $limit = 15;
         $count = count($codes);
-        if($count > $limit) {
-            $parts = array_chunk($codes, $limit);
-            $books = array();
-            foreach($parts as $p) {
-                // if we use array_merge here the numerical keys (book code) will be lost
-                $books += self::getBooks($p, $field);
-            }
-            return $books;
-        }
 
         $bs = self::getLastInstance();
-        $bs->addOrQuery($codes, $field);
+        $parts = $count <= $limit ? [$codes] : array_chunk($codes, $limit);
+        $books = [];
+        foreach($parts as $p) {
+            // if we use array_merge here the numerical keys (book code) will be lost
+            $bs->addOrQuery($codes, $field);
+            $results = $bs->getResults(0, $count);
+            $foundBooks = $results['books'];
+            $books += $foundBooks;
+        }
 
-        $results = $bs->getResults(0, $count);
-        return $results['books'];
+        return $books;
     }
 
     public static function getTerms($field) {