diff --git a/cmd/tlserver/main.go b/cmd/tlserver/main.go
index ed24f6cd..6e1bc5d5 100644
--- a/cmd/tlserver/main.go
+++ b/cmd/tlserver/main.go
@@ -106,7 +106,6 @@ func (cmd *ServerCommand) AddFlags(fl *pflag.FlagSet) {
 	fl.BoolVar(&cmd.LoadAdmins, "load-admins", false, "Load admin polygons from database into memory")
 	fl.IntVar(&cmd.LoaderBatchSize, "loader-batch-size", 100, "GraphQL Loader batch size")
 	fl.IntVar(&cmd.LoaderStopTimeBatchSize, "loader-stop-time-batch-size", 1, "GraphQL Loader batch size for StopTimes")
-
 }
 
 func (cmd *ServerCommand) Parse(args []string) error {
diff --git a/internal/clock/swcache.go b/internal/clock/swcache.go
index 436905be..f13444f8 100644
--- a/internal/clock/swcache.go
+++ b/internal/clock/swcache.go
@@ -68,7 +68,9 @@ func (f *ServiceWindowCache) Get(ctx context.Context, fvid int) (ServiceWindow,
 	}
 
 	// Add to cache
+	f.lock.Lock()
 	f.fvslWindows[fvid] = a
+	f.lock.Unlock()
 	return a, true, err
 }