diff --git a/modules/services/buildkite-agents.nix b/modules/services/buildkite-agents.nix
index 094f2c9d..79ee1984 100644
--- a/modules/services/buildkite-agents.nix
+++ b/modules/services/buildkite-agents.nix
@@ -235,7 +235,11 @@ in
         ##     don't end up in the Nix store.
         script = let
           sshDir = "${cfg.dataDir}/.ssh";
-          tagStr = lib.concatStringsSep "," (lib.mapAttrsToList (name: value: "${name}=${value}") cfg.tags);
+          tagStr = name: value:
+            if lib.isList value
+            then lib.concatStringsSep "," (builtins.map (v: "${name}=${v}") value)
+            else "${name}=${value}";
+          tagsStr = lib.concatStringsSep "," (lib.mapAttrsToList tagStr cfg.tags);
         in
           optionalString (cfg.privateSshKeyPath != null) ''
             mkdir -m 0700 -p "${sshDir}"
@@ -245,7 +249,7 @@ in
             token="$(cat ${toString cfg.tokenPath})"
             name="${cfg.name}"
             shell="${cfg.shell}"
-            tags="${tagStr}"
+            tags="${tagsStr}"
             build-path="${cfg.dataDir}/builds"
             hooks-path="${cfg.hooksPath}"
             ${cfg.extraConfig}