diff --git a/outlines/models/openai.py b/outlines/models/openai.py
index dd1c73b24..16126acb0 100644
--- a/outlines/models/openai.py
+++ b/outlines/models/openai.py
@@ -15,6 +15,7 @@
 
 if TYPE_CHECKING:
     from openai import AsyncOpenAI
+    from openai.types.completion_usage import CompletionUsage
 
 
 @dataclass(frozen=True)
@@ -281,23 +282,19 @@ async def generate_chat(
     system_prompt: Union[str, None],
     client: "AsyncOpenAI",
     config: OpenAIConfig,
-) -> Tuple[np.ndarray, int]:
+) -> Tuple[np.ndarray, "CompletionUsage"]:
+    system_message = (
+        [{"role": "system", "content": system_prompt}] if system_prompt else []
+    )
+
     responses = await client.chat.completions.create(
-        messages=(
-            [{"role": "system", "content": system_prompt}] if system_prompt else []
-        )
-        + [{"role": "user", "content": prompt}],
+        messages=system_message + [{"role": "user", "content": prompt}],
         **asdict(config),  # type: ignore
     )
 
-    if config.n == 1:
-        results = np.array([responses.choices[0].message.content])
-    else:
-        results = np.array(
-            [responses.choices[i].message.content for i in range(config.n)]
-        )
+    results = np.array([responses.choices[i].message.content for i in range(config.n)])
 
-    return results, responses.usage.total_tokens
+    return results, responses.usage
 
 
 openai = OpenAI
diff --git a/pyproject.toml b/pyproject.toml
index 87493cb03..48f3e9dd4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -92,7 +92,7 @@ module = [
     "jinja2",
     "joblib.*",
     "jsonschema.*",
-    "openai",
+    "openai.*",
     "nest_asyncio",
     "numpy.*",
     "perscache.*",