diff --git a/algo/evselector/DigiEventSelector.h b/algo/evselector/DigiEventSelector.h
index a19e98c681c5bf0f72a541f07cf83206adba7727..59ead9e1b2a447f0aebba1e4508f06bd0633898c 100644
--- a/algo/evselector/DigiEventSelector.h
+++ b/algo/evselector/DigiEventSelector.h
@@ -64,7 +64,7 @@ namespace cbm::algo::evbuild
 
 
   private:                            // members
-    DigiEventSelectorParams fParams;  ///< Selection parameters
+    const DigiEventSelectorParams fParams;  ///< Selection parameters
   };
 
 }  // namespace cbm::algo::evbuild