diff --git a/haystack_experimental/components/extractors/llm_metadata_extractor.py b/haystack_experimental/components/extractors/llm_metadata_extractor.py
index a03a9523..1bc4ad7e 100644
--- a/haystack_experimental/components/extractors/llm_metadata_extractor.py
+++ b/haystack_experimental/components/extractors/llm_metadata_extractor.py
@@ -149,7 +149,7 @@ def __init__( # pylint: disable=R0917
 
     @staticmethod
     def _init_generator(
-            generator_api: Union[str,LLMProvider],
+            generator_api: LLMProvider,
             generator_api_params: Optional[Dict[str, Any]]
     ) -> Union[OpenAIGenerator, AzureOpenAIGenerator, AmazonBedrockGenerator, VertexAIGeminiGenerator]:
         """