diff --git a/nixos/modules/misc/version.nix b/nixos/modules/misc/version.nix
index e9ee476d36a9..1b519d3e6eef 100644
--- a/nixos/modules/misc/version.nix
+++ b/nixos/modules/misc/version.nix
@@ -26,10 +26,10 @@ with pkgs.lib;
   config = {
 
     system.nixosVersion =
-      mkDefault (builtins.readFile "${pkgs.path}/.version" + config.system.nixosVersionSuffix);
+      mkDefault (builtins.readFile "${toString pkgs.path}/.version" + config.system.nixosVersionSuffix);
 
     system.nixosVersionSuffix =
-      let suffixFile = "${pkgs.path}/.version-suffix"; in
+      let suffixFile = "${toString pkgs.path}/.version-suffix"; in
       mkDefault (if builtins.pathExists suffixFile then builtins.readFile suffixFile else "pre-git");
 
     # Note: code names must only increase in alphabetical order.