diff --git a/src/Search/Sorting/Sort.php b/src/Search/Sorting/Sort.php
index 8a6ec4b..cdfeb52 100644
--- a/src/Search/Sorting/Sort.php
+++ b/src/Search/Sorting/Sort.php
@@ -65,7 +65,7 @@ public function toDSL(): array
 
         $details['order'] = $this->order;
 
-        return [$this->field => $details];
+        return [$this->script !== null ? '_script' : $this->field => $details];
     }
 
     public function __toString(): string
diff --git a/src/Search/Sorting/SortBuilder.php b/src/Search/Sorting/SortBuilder.php
index a887efe..c990c7b 100644
--- a/src/Search/Sorting/SortBuilder.php
+++ b/src/Search/Sorting/SortBuilder.php
@@ -49,7 +49,7 @@ public function sortBy(string $field, string $order = SortOrder::ASC, ?string $m
     public function sortByScript(Script $script, string $type = ScriptSortType::NUMBER, string $order = SortOrder::ASC): static
     {
         $sort = new Sort(
-            field: '_script',
+            field: '_script' . md5(json_encode($script->toDSL())),
             order: $order,
             type: $type,
             script: $script,