diff --git a/server/text_generation_server/models/__init__.py b/server/text_generation_server/models/__init__.py
index 1bbff16a4..39d1d58ec 100644
--- a/server/text_generation_server/models/__init__.py
+++ b/server/text_generation_server/models/__init__.py
@@ -281,9 +281,10 @@ def get_model(
                 )
 
     if model_type == "mistral":
-        if (config_dict["sliding_window"] is None and FLASH_ATTENTION) or (
-            config_dict["sliding_window"] > 0 and HAS_FLASH_ATTN_V2_CUDA
-        ):
+        sliding_window = config_dict.get("sliding_window", -1)
+        if (
+            (sliding_window is None or sliding_window == -1) and FLASH_ATTENTION
+        ) or HAS_FLASH_ATTN_V2_CUDA:
             return FlashMistral(
                 model_id,
                 revision,
@@ -293,9 +294,10 @@ def get_model(
             )
 
     if model_type == "mixtral":
-        if (config_dict["sliding_window"] is None and FLASH_ATTENTION) or (
-            config_dict["sliding_window"] > 0 and HAS_FLASH_ATTN_V2_CUDA
-        ):
+        sliding_window = config_dict.get("sliding_window", -1)
+        if (
+            (sliding_window is None or sliding_window == -1) and FLASH_ATTENTION
+        ) or HAS_FLASH_ATTN_V2_CUDA:
             return FlashMixtral(
                 model_id,
                 revision,
diff --git a/server/text_generation_server/models/custom_modeling/flash_mistral_modeling.py b/server/text_generation_server/models/custom_modeling/flash_mistral_modeling.py
index c85624f3a..0fc4e1b39 100644
--- a/server/text_generation_server/models/custom_modeling/flash_mistral_modeling.py
+++ b/server/text_generation_server/models/custom_modeling/flash_mistral_modeling.py
@@ -60,7 +60,7 @@ class MistralConfig(PretrainedConfig):
         pretraining_tp=1,
         tie_word_embeddings=False,
         rope_theta=10000.0,
-        sliding_window=4096,
+        sliding_window=None,
         **kwargs,
     ):
         self.vocab_size = vocab_size
diff --git a/server/text_generation_server/models/custom_modeling/flash_mixtral_modeling.py b/server/text_generation_server/models/custom_modeling/flash_mixtral_modeling.py
index b468d09b2..61488ec4f 100644
--- a/server/text_generation_server/models/custom_modeling/flash_mixtral_modeling.py
+++ b/server/text_generation_server/models/custom_modeling/flash_mixtral_modeling.py
@@ -72,7 +72,7 @@ class MixtralConfig(PretrainedConfig):
         pretraining_tp=1,
         tie_word_embeddings=False,
         rope_theta=10000.0,
-        sliding_window=4096,
+        sliding_window=None,
         num_experts_per_tok=2,
         num_local_experts=8,
         **kwargs,
diff --git a/server/text_generation_server/models/model.py b/server/text_generation_server/models/model.py
index cb358672e..cec9eafa8 100644
--- a/server/text_generation_server/models/model.py
+++ b/server/text_generation_server/models/model.py
@@ -33,7 +33,7 @@ class Model(ABC):
         self.device = device
         self.rank = rank
         self.world_size = world_size
-        self.sliding_window = sliding_window
+        self.sliding_window = sliding_window if sliding_window != -1 else None
 
         if speculate is None:
             speculate = get_speculate()