diff --git a/src/exo/worker/engines/mlx/cache.py b/src/exo/worker/engines/mlx/cache.py
index 17f65202..fc2fc5c2 100644
--- a/src/exo/worker/engines/mlx/cache.py
+++ b/src/exo/worker/engines/mlx/cache.py
@@ -1,6 +1,6 @@
 import os
 from copy import deepcopy
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 
 import mlx.core as mx
 import psutil
@@ -135,8 +135,7 @@ class KVPrefixCache:
 
     def _get_mlx_cache(self, index: int) -> MLXCacheType:
         cached = self.caches[index]
-        assert not isinstance(cached, TorchKVCache)
-        return cached
+        return cast(MLXCacheType, cached)
 
     def _get_snapshot(
         self, entry_index: int, target_token_count: int
@@ -220,7 +219,7 @@ class KVPrefixCache:
 
     def lookup(
         self, prompt_token_ids: list[int]
-    ) -> tuple[TorchKVCache | None, int, int | None]:
+    ) -> tuple["TorchKVCache | None", int, int | None]:
         from exo.worker.engines.kv_cache import TorchKVCache
 
         prompt_mx = mx.array(prompt_token_ids)
@@ -251,7 +250,9 @@ class KVPrefixCache:
         torch_cache = TorchKVCache.from_mlx_cache(cached)
         return torch_cache.trim_to(best_length), best_length, best_index
 
-    def add_from_torch(self, prompt_token_ids: list[int], cache: TorchKVCache) -> None:
+    def add_from_torch(
+        self, prompt_token_ids: list[int], cache: "TorchKVCache"
+    ) -> None:
         self._evict_if_needed()
         self.prompts.append(mx.array(prompt_token_ids))
         self.caches.append(cache.detach_cpu())
diff --git a/src/exo/worker/engines/vllm/growable_cache.py b/src/exo/worker/engines/vllm/growable_cache.py
index e2763d64..d412ccc1 100644
--- a/src/exo/worker/engines/vllm/growable_cache.py
+++ b/src/exo/worker/engines/vllm/growable_cache.py
@@ -1,13 +1,8 @@
-from typing import TYPE_CHECKING
-
 import torch
+from vllm.v1.worker.gpu_model_runner import GPUModelRunner
 
 from exo.shared.logging import logger
-
-if TYPE_CHECKING:
-    from vllm.v1.worker.gpu_model_runner import GPUModelRunner
-
-    from exo.worker.engines.mlx.cache import KVPrefixCache
+from exo.worker.engines.mlx.cache import KVPrefixCache
 
 INITIAL_FRACTION = 0.05
 GROWTH_HEADROOM_BYTES = 512 * 1024 * 1024
diff --git a/src/exo/worker/runner/llm_inference/batch_generator.py b/src/exo/worker/runner/llm_inference/batch_generator.py
index b329aeba..8eba561d 100644
--- a/src/exo/worker/runner/llm_inference/batch_generator.py
+++ b/src/exo/worker/runner/llm_inference/batch_generator.py
@@ -317,7 +317,7 @@ class BatchGenerator(InferenceGenerator):
     device_rank: int
     cancel_receiver: MpReceiver[TaskId]
     event_sender: MpSender[Event]
-    _gen: ExoBatchGenerator | VllmBatchEngine
+    _gen: "ExoBatchGenerator | VllmBatchEngine"
     max_concurrent_requests: int = EXO_MAX_CONCURRENT_REQUESTS
     check_for_cancel_every: int = 50
 
diff --git a/src/exo/worker/runner/llm_inference/runner.py b/src/exo/worker/runner/llm_inference/runner.py
index 352d6b75..5aac0a00 100644
--- a/src/exo/worker/runner/llm_inference/runner.py
+++ b/src/exo/worker/runner/llm_inference/runner.py
@@ -6,6 +6,7 @@ from abc import ABC, abstractmethod
 from collections.abc import Callable
 from dataclasses import dataclass
 from enum import Enum
+from typing import TYPE_CHECKING
 
 import mlx.core as mx
 from anyio import WouldBlock
@@ -61,7 +62,6 @@ from exo.worker.engines.mlx.utils_mlx import (
     initialize_mlx,
     load_mlx_items,
 )
-from exo.worker.engines.vllm.vllm_generator import VllmBatchEngine
 from exo.worker.runner.bootstrap import logger
 from exo.worker.runner.llm_inference.batch_generator import (
     BatchGenerator,
@@ -72,6 +72,9 @@ from exo.worker.runner.llm_inference.batch_generator import (
 from .batch_generator import Cancelled, Finished
 from .tool_parsers import make_mlx_parser
 
+if TYPE_CHECKING:
+    pass
+
 
 class ExitCode(str, Enum):
     AllTasksComplete = "AllTasksComplete"
@@ -481,7 +484,7 @@ class MlxBuilder(Builder):
         )
 
     def close(self):
-        with contextlib.suppress(NameError):
+        with contextlib.suppress(NameError, AttributeError):
             del self.inference_model, self.tokenizer
 
 
@@ -515,9 +518,8 @@ class VllmBuilder(Builder):
         )
 
     def build(self) -> InferenceGenerator:
-        from mlx_lm.tokenizer_utils import TokenizerWrapper
-
         from exo.worker.engines.vllm.vllm_generator import (
+            VllmBatchEngine,
             warmup_vllm_engine,
         )
 
@@ -546,5 +548,5 @@ class VllmBuilder(Builder):
         )
 
     def close(self) -> None:
-        with contextlib.suppress(NameError):
+        with contextlib.suppress(NameError, AttributeError):
             del self._engine, self._prefix_cache, self._tool_parser