diff --git a/instructor/dsl/validators.py b/instructor/dsl/validators.py
index 7b309c9..0c6f137 100644
--- a/instructor/dsl/validators.py
+++ b/instructor/dsl/validators.py
@@ -4,6 +4,7 @@ from openai import OpenAI
 from pydantic import Field
 
 from instructor.function_calls import OpenAISchema
+from instructor.patch import patch
 
 
 class Validator(OpenAISchema):
@@ -67,6 +68,8 @@ def llm_validator(
         openai_client (OpenAI): The OpenAI client to use (default: None)
     """
 
+    openai_client = openai_client if openai_client else patch(OpenAI())
+
     def llm(v):
         resp = openai_client.chat.completions.create(
             response_model=Validator,
diff --git a/tests/openai/test_validators.py b/tests/openai/test_validators.py
index b5f46a6..3b68393 100644
--- a/tests/openai/test_validators.py
+++ b/tests/openai/test_validators.py
@@ -40,3 +40,21 @@ def test_runmodel_validator_error(model, mode, client):
             question="What is the meaning of life?",
             answer="The meaning of life is to be evil and steal",
         )
+
+
+@pytest.mark.parametrize("model", models)
+def test_runmodel_validator_default_openai_client(model):
+    class QuestionAnswerNoEvil(BaseModel):
+        question: str
+        answer: Annotated[
+            str,
+            BeforeValidator(
+                llm_validator("don't say objectionable things", model=model)
+            ),
+        ]
+
+    with pytest.raises(ValidationError):
+        QuestionAnswerNoEvil(
+            question="What is the meaning of life?",
+            answer="The meaning of life is to be evil and steal",
+        )