diff --git a/src/transformers/generation/utils.py b/src/transformers/generation/utils.py
index 6e6d5b8bdce71d..53cd2df3a49c84 100644
--- a/src/transformers/generation/utils.py
+++ b/src/transformers/generation/utils.py
@@ -1452,10 +1452,11 @@ def _prepare_generated_length(
         ):
             generation_config.max_length -= inputs_tensor.shape[1]
         elif has_default_max_length:  # by default let's always generate 20 new tokens
-            generation_config.max_length = generation_config.max_length + input_ids_length
-            max_position_embeddings = getattr(self.config, "max_position_embeddings", None)
-            if max_position_embeddings is not None:
-                generation_config.max_length = min(generation_config.max_length, max_position_embeddings)
+            if generation_config.max_length == GenerationConfig().max_length:
+                generation_config.max_length = generation_config.max_length + input_ids_length
+                max_position_embeddings = getattr(self.config, "max_position_embeddings", None)
+                if max_position_embeddings is not None:
+                    generation_config.max_length = min(generation_config.max_length, max_position_embeddings)
 
         # same for min length
         if generation_config.min_new_tokens is not None: