diff --git a/flake.nix b/flake.nix
index 6c13f447..f26ec96e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -52,7 +52,7 @@
 
             versionInfo = {
               commitHash = if (self ? rev) then self.rev else self.dirtyRev;
-              commitDate = lib.readFile "${prev.runCommand "timestamp" { env.when = self.lastModified; } "echo -n `date -d @$when --iso-8601=s` > $out"}";
+              commitDate = self.lastModified;
             };
           };
         });
@@ -85,7 +85,7 @@
               inherit pkgs lib;
               versionInfo = {
                 commitHash = if (self ? rev) then self.rev else self.dirtyRev;
-                commitDate = lib.readFile "${pkgs.runCommand "timestamp" { env.when = self.lastModified; } "echo -n `date -d @$when --iso-8601=s` > $out"}";
+                commitDate = self.lastModified;
               };
             });
           };
diff --git a/nix/pkgs/frontend.nix b/nix/pkgs/frontend.nix
index e90f2aec..3f4caa2b 100644
--- a/nix/pkgs/frontend.nix
+++ b/nix/pkgs/frontend.nix
@@ -41,10 +41,10 @@ pkgs.buildNpmPackage (lib.fix (self: {
   };
 
   preBuild = let
-    versionExports = ([ ] ++ (lib.optional (versionInfo ? commitHash)
-      ''export COMMIT_HASH="${versionInfo.commitHash}"'')
-      ++ (lib.optional (versionInfo ? commitDate)
-        ''export COMMIT_DATE="${versionInfo.commitDate}"''));
+    versionExports = ([ ]
+      ++ (lib.optional (versionInfo ? commitHash) ''export COMMIT_HASH="${versionInfo.commitHash}"'')
+      ++ (lib.optional (versionInfo ? commitDate) ''export COMMIT_DATE="$(date -d @${builtins.toString versionInfo.commitDate} --iso-8601=s)"'')
+    );
   in ''
     ${lib.concatStringsSep "\n" versionExports}
   '';