diff --git a/libs/langchain/langchain/chains/combine_documents/base.py b/libs/langchain/langchain/chains/combine_documents/base.py
index 90e965996de..00b6002da0e 100644
--- a/libs/langchain/langchain/chains/combine_documents/base.py
+++ b/libs/langchain/langchain/chains/combine_documents/base.py
@@ -22,11 +22,11 @@ DOCUMENTS_KEY = "context"
 DEFAULT_DOCUMENT_PROMPT = PromptTemplate.from_template("{page_content}")
 
 
-def _validate_prompt(prompt: BasePromptTemplate) -> None:
-    if DOCUMENTS_KEY not in prompt.input_variables:
+def _validate_prompt(prompt: BasePromptTemplate, document_variable_name: str) -> None:
+    if document_variable_name not in prompt.input_variables:
         raise ValueError(
-            f"Prompt must accept {DOCUMENTS_KEY} as an input variable. Received prompt "
-            f"with input variables: {prompt.input_variables}"
+            f"Prompt must accept {document_variable_name} as an input variable. "
+            f"Received prompt with input variables: {prompt.input_variables}"
         )
 
 
diff --git a/libs/langchain/langchain/chains/combine_documents/stuff.py b/libs/langchain/langchain/chains/combine_documents/stuff.py
index 5ffd86c9718..cdecec0f40b 100644
--- a/libs/langchain/langchain/chains/combine_documents/stuff.py
+++ b/libs/langchain/langchain/chains/combine_documents/stuff.py
@@ -76,7 +76,7 @@ def create_stuff_documents_chain(
             chain.invoke({"context": docs})
     """  # noqa: E501
 
-    _validate_prompt(prompt)
+    _validate_prompt(prompt, document_variable_name)
     _document_prompt = document_prompt or DEFAULT_DOCUMENT_PROMPT
     _output_parser = output_parser or StrOutputParser()