diff --git a/src/libutil/logging.hh b/src/libutil/logging.hh
index 1e0c73567..08a116175 100644
--- a/src/libutil/logging.hh
+++ b/src/libutil/logging.hh
@@ -81,6 +81,8 @@ struct Activity
 
     Activity(Logger & logger, ActivityType type, const std::string & s = "");
 
+    Activity(const Activity & act) = delete;
+
     ~Activity()
     { logger.stopActivity(id); }