diff --git a/libs/langchain/langchain/chains/query_constructor/base.py b/libs/langchain/langchain/chains/query_constructor/base.py
index d6c38d5319d..ecbffe18163 100644
--- a/libs/langchain/langchain/chains/query_constructor/base.py
+++ b/libs/langchain/langchain/chains/query_constructor/base.py
@@ -48,7 +48,7 @@ class StructuredQueryOutputParser(BaseOutputParser[StructuredQuery]):
             expected_keys = ["query", "filter"]
             allowed_keys = ["query", "filter", "limit"]
             parsed = parse_and_check_json_markdown(text, expected_keys)
-            if len(parsed["query"]) == 0:
+            if parsed["query"] is None or len(parsed["query"]) == 0:
                 parsed["query"] = " "
             if parsed["filter"] == "NO_FILTER" or not parsed["filter"]:
                 parsed["filter"] = None