diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index b5b060d95..738e7051e 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -227,7 +227,7 @@ void LocalDerivationGoal::tryLocalBuild()
         if (!buildUser) {
             if (!actLock)
                 actLock = std::make_unique<Activity>(*logger, lvlWarn, actBuildWaiting,
-                    fmt("waiting for UID to build '%s'", yellowtxt(worker.store.printStorePath(drvPath))));
+                    fmt("waiting for a free build user ID for '%s'", yellowtxt(worker.store.printStorePath(drvPath))));
             worker.waitForAWhile(shared_from_this());
             return;
         }