diff --git a/libs/core/langchain_core/messages/base.py b/libs/core/langchain_core/messages/base.py
index 08f6dc82859..baab0379066 100644
--- a/libs/core/langchain_core/messages/base.py
+++ b/libs/core/langchain_core/messages/base.py
@@ -4,7 +4,7 @@ from __future__ import annotations
 
 from typing import TYPE_CHECKING, Any, Optional, Union, cast
 
-from pydantic import ConfigDict, Field, field_validator
+from pydantic import ConfigDict, Field
 
 from langchain_core.load.serializable import Serializable
 from langchain_core.utils import get_bolded_text
@@ -52,7 +52,7 @@ class BaseMessage(Serializable):
     model implementation.
     """
 
-    id: Optional[str] = None
+    id: Optional[str] = Field(default=None, coerce_numbers_to_str=True)
     """An optional unique identifier for the message. This should ideally be
     provided by the provider/model which created the message."""
 
@@ -60,13 +60,6 @@ class BaseMessage(Serializable):
         extra="allow",
     )
 
-    @field_validator("id", mode="before")
-    def cast_id_to_str(cls, id_value: Any) -> Optional[str]:
-        """Coerce the id field to a string."""
-        if id_value is not None:
-            return str(id_value)
-        return id_value
-
     def __init__(
         self, content: Union[str, list[Union[str, dict]]], **kwargs: Any
     ) -> None: