diff --git a/extensions/openai/typing.py b/extensions/openai/typing.py
index 90366270..56d91582 100644
--- a/extensions/openai/typing.py
+++ b/extensions/openai/typing.py
@@ -2,7 +2,7 @@ import json
 import time
 from typing import Dict, List, Optional
 
-from pydantic import BaseModel, Field, field_validator, validator
+from pydantic import BaseModel, Field, model_validator, validator
 
 
 class GenerationOptions(BaseModel):
@@ -116,16 +116,11 @@ class CompletionRequestParams(BaseModel):
     top_p: float | None = 1
     user: str | None = Field(default=None, description="Unused parameter.")
 
-    @field_validator('prompt', 'messages')
-    @classmethod
-    def validate_prompt_or_messages(cls, v, info):
-        """Ensure either 'prompt' or 'messages' is provided for completions."""
-        if info.field_name == 'prompt':  # If we're validating 'prompt', check if neither prompt nor messages will be set
-            messages = info.data.get('messages')
-            if v is None and messages is None:
-                raise ValueError("Either 'prompt' or 'messages' must be provided")
-
-        return v
+    @model_validator(mode='after')
+    def validate_prompt_or_messages(self):
+        if self.prompt is None and self.messages is None:
+            raise ValueError("Either 'prompt' or 'messages' must be provided")
+        return self
 
 
 class CompletionRequest(GenerationOptions, CompletionRequestParams):