diff --git a/server/lorax_server/models/flash_causal_lm.py b/server/lorax_server/models/flash_causal_lm.py
index 4f5cc842..c064cbe5 100644
--- a/server/lorax_server/models/flash_causal_lm.py
+++ b/server/lorax_server/models/flash_causal_lm.py
@@ -1352,7 +1352,7 @@ def warmup(self, batch: FlashCausalLMBatch, max_new_tokens: int, embedding_model
             torch.cuda.synchronize(self.device)
 
         logger.info(f'Post warmup cuda memory: {get_cuda_free_memory(self.device, 1) / (1024 ** 3):.2f} GB')
-        del self.model_graph_wrapper
+        self.model_graph_wrapper = None
         self.kv_cache = []
         torch.cuda.synchronize(self.device)
         torch.cuda.empty_cache()