diff --git a/go/nix/bcacheup/bcacheup.go b/go/nix/bcacheup/bcacheup.go
index f2a9cc5d04..5bbbd51143 100644
--- a/go/nix/bcacheup/bcacheup.go
+++ b/go/nix/bcacheup/bcacheup.go
@@ -32,7 +32,7 @@ import (
 var (
 	blobURLFlag              = flag.String("cache_url", "", "Cache URL")
 	storeDBFlag              = flag.String("nix_store_db", nixstore.DefaultStoreDB, "Path to the nix store database")
-	stateSummaryIntervalFlag = flag.Interval("state_summary_interval", 10*time.Second, "Time between state summary outputs.")
+	stateSummaryIntervalFlag = flag.Duration("state_summary_interval", 10*time.Second, "Time between state summary outputs.")
 )
 
 var (