diff --git a/modules/system/version.nix b/modules/system/version.nix
index 087e8dd..72aeea7 100644
--- a/modules/system/version.nix
+++ b/modules/system/version.nix
@@ -8,7 +8,7 @@ let
   defaultStateVersion = options.system.stateVersion.default;
 
   gitCommitId = lib.substring 0 7 (commitIdFromGitRepo gitRepo);
-  gitRepo = "${toString pkgs.path}/.git";
+  gitRepo = "${toString pkgs.path}/.git/";
   releaseFile = "${toString pkgs.path}/.version";
   revisionFile = "${toString pkgs.path}/.git-revision";
   suffixFile = "${toString pkgs.path}/.version-suffix";
@@ -71,8 +71,8 @@ in
     # These defaults are set here rather than up there so that
     # changing them would not rebuild the manual
     system.nixpkgsVersion = mkDefault (cfg.nixpkgsRelease + cfg.nixpkgsVersionSuffix);
-    system.nixpkgsRevision = mkIf (pathIsDirectory gitRepo) (mkDefault gitCommitId);
-    system.nixpkgsVersionSuffix = mkIf (pathIsDirectory gitRepo) (mkDefault (".git." + gitCommitId));
+    system.nixpkgsRevision = mkIf (builtins.pathExists gitRepo) (mkDefault gitCommitId);
+    system.nixpkgsVersionSuffix = mkIf (builtins.pathExists gitRepo) (mkDefault (".git." + gitCommitId));
 
     assertions = [ { assertion = cfg.stateVersion <= defaultStateVersion; message = "system.stateVersion = ${toString cfg.stateVersion}; is not a valid value"; } ];