diff --git a/algo/base/ChainContext.h b/algo/base/ChainContext.h
index 0ed47dcc3853f09f162a2111312db2f9fb2244e4..19f9e15fb6138e97806a35b87e3d1b19b78ad5b8 100644
--- a/algo/base/ChainContext.h
+++ b/algo/base/ChainContext.h
@@ -15,7 +15,7 @@ namespace cbm::algo
   struct ChainContext {
     Options opts;
     RecoParams recoParams;
-    std::optional<cbm::Monitor> monitor;
+    std::optional<cbm::Monitor> monitor;  //!
   };
 }  // namespace cbm::algo