diff --git a/src/middleware.py b/src/middleware.py
index d87190c..242d049 100644
--- a/src/middleware.py
+++ b/src/middleware.py
@@ -148,7 +148,7 @@ class RequestValidationMiddleware(BaseHTTPMiddleware):
         # -------------------------
         # 3. Query param inspection
         # -------------------------
-        pagination_size_keys = {"size", "itemsPerPage", "per_page", "limit"}
+        pagination_size_keys = {"size", "itemsPerPage", "per_page", "limit", "items_per_page"}
         for key, value in params:
             if value:
                 inspect_value(value, f"query param '{key}'")