diff --git a/src/build-remote/build-remote.cc b/src/build-remote/build-remote.cc
index 350bd6cef..68af3e966 100644
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@@ -75,11 +75,11 @@ static int main_build_remote(int argc, char * * argv)
 
         /* It would be more appropriate to use $XDG_RUNTIME_DIR, since
            that gets cleared on reboot, but it wouldn't work on macOS. */
-        currentLoad = "/current-load";
+        auto currentLoadName = "/current-load";
         if (auto localStore = store.dynamic_pointer_cast<LocalFSStore>())
-            currentLoad = std::string { localStore->stateDir } + currentLoad;
+            currentLoad = std::string { localStore->stateDir } + currentLoadName;
         else
-            currentLoad = settings.nixStateDir + currentLoad;
+            currentLoad = settings.nixStateDir + currentLoadName;
 
         std::shared_ptr<Store> sshStore;
         AutoCloseFD bestSlotLock;
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 953e241d8..fa8b99118 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -3291,7 +3291,7 @@ void DerivationGoal::registerOutputs()
 
         auto localStoreP = dynamic_cast<LocalStore *>(&worker.store);
         if (!localStoreP)
-            Unsupported("Can only register outputs with local store");
+            throw Unsupported("can only register outputs with local store, but this is %s", worker.store.getUri());
         auto & localStore = *localStoreP;
 
         if (buildMode == bmCheck) {
@@ -3426,7 +3426,7 @@ void DerivationGoal::registerOutputs()
     {
         auto localStoreP = dynamic_cast<LocalStore *>(&worker.store);
         if (!localStoreP)
-            Unsupported("Can only register outputs with local store");
+            throw Unsupported("can only register outputs with local store, but this is %s", worker.store.getUri());
         auto & localStore = *localStoreP;
 
         ValidPathInfos infos2;