diff --git a/libs/core/langchain_core/prompts/base.py b/libs/core/langchain_core/prompts/base.py
index 8ba8e56071..66c65b9b5a 100644
--- a/libs/core/langchain_core/prompts/base.py
+++ b/libs/core/langchain_core/prompts/base.py
@@ -129,7 +129,7 @@ class BasePromptTemplate(
             "PromptInput", **{**required_input_variables, **optional_input_variables}
         )
 
-    def _validate_input(self, inner_input: Dict) -> Dict:
+    def _validate_input(self, inner_input: Any) -> Dict:
         if not isinstance(inner_input, dict):
             if len(self.input_variables) == 1:
                 var_name = self.input_variables[0]