diff --git a/src/openai/_exceptions.py b/src/openai/_exceptions.py
index 86f44b0e15..22055e40d8 100644
--- a/src/openai/_exceptions.py
+++ b/src/openai/_exceptions.py
@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any, Optional, cast
+from typing import TYPE_CHECKING, Any, Union, Optional, cast
 from typing_extensions import Literal
 
 import httpx
@@ -60,7 +60,7 @@ class APIError(OpenAIError):
     If there was no response associated with this error then it will be `None`.
     """
 
-    code: Optional[str] = None
+    code: Optional[Union[str, int]] = None
     param: Optional[str] = None
     type: Optional[str]
 
@@ -71,7 +71,8 @@ def __init__(self, message: str, request: httpx.Request, *, body: object | None)
         self.body = body
 
         if is_dict(body):
-            self.code = cast(Any, construct_type(type_=Optional[str], value=body.get("code")))
+            code_value = body.get("code")
+            self.code = code_value if isinstance(code_value, (str, int)) else None
             self.param = cast(Any, construct_type(type_=Optional[str], value=body.get("param")))
             self.type = cast(Any, construct_type(type_=str, value=body.get("type")))
         else:
diff --git a/tests/lib/test_exceptions.py b/tests/lib/test_exceptions.py
new file mode 100644
index 0000000000..8ec89be5c0
--- /dev/null
+++ b/tests/lib/test_exceptions.py
@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+import httpx
+
+from openai._exceptions import BadRequestError
+
+
+def _make_error(body: dict[str, object]) -> BadRequestError:
+    request = httpx.Request("POST", "https://api.openai.com/v1/chat/completions")
+    response = httpx.Response(400, request=request)
+    return BadRequestError(message="test error", response=response, body=body)
+
+
+def test_integer_error_code_is_preserved() -> None:
+    # The OpenAI API can return integer error codes (e.g. 1006). Constructing
+    # the error from such a body must keep the raw int: Pydantic v1 union
+    # coercion would otherwise stringify it to "1006".
+    err = _make_error({"message": "test error", "code": 123})
+    assert err.code == 123
+    assert isinstance(err.code, int)
+
+
+def test_string_error_code_is_preserved() -> None:
+    # String codes (the common case) must keep working unchanged.
+    err = _make_error({"message": "test error", "code": "rate_limit_exceeded"})
+    assert err.code == "rate_limit_exceeded"
+
+
+def test_missing_or_invalid_error_code_is_none() -> None:
+    assert _make_error({"message": "test error"}).code is None
+    assert _make_error({"message": "test error", "code": {"nested": True}}).code is None