diff --git a/pkgs/servers/monitoring/prometheus/default.nix b/pkgs/servers/monitoring/prometheus/default.nix
index b0de5b271d4..2852fb2afc2 100644
--- a/pkgs/servers/monitoring/prometheus/default.nix
+++ b/pkgs/servers/monitoring/prometheus/default.nix
@@ -44,10 +44,10 @@ in buildGoPackage rec {
     ln -s ${webui} web/ui/static/react
   '';
 
+  buildFlags = "-tags=builtinassets";
   buildFlagsArray = let
     t = "${goPackagePath}/vendor/github.com/prometheus/common/version";
   in [
-    "-tags=builtinassets"
     ''
       -ldflags=
          -X ${t}.Version=${version}