diff --git a/aab/builder.py b/aab/builder.py
index 5c3805c..7dfe595 100644
--- a/aab/builder.py
+++ b/aab/builder.py
@@ -77,7 +77,7 @@ class AddonBuilder:
         self._config = Config()
         self._path_dist_module = PATH_DIST / "src" / self._config["module_name"]

-    def build(self, qt_versions: List[QtVersion], disttype="local", pyenv=None):
+    def build(self, qt_versions: List[QtVersion], disttype="local", pyenv=None, modtime=None):
         logging.info(
             "\n--- Building %s %s for %s ---\n",
             self._config["display_name"],
@@ -86,7 +86,7 @@ class AddonBuilder:
         )

         self.create_dist()
-        self.build_dist(qt_versions=qt_versions, disttype=disttype, pyenv=pyenv)
+        self.build_dist(qt_versions=qt_versions, disttype=disttype, pyenv=pyenv, modtime=modtime)

         return self.package_dist(qt_versions=qt_versions, disttype=disttype)

@@ -102,7 +102,7 @@ class AddonBuilder:
         PATH_DIST.mkdir(parents=True)
         Git().archive(self._version, PATH_DIST)

-    def build_dist(self, qt_versions: List[QtVersion], disttype="local", pyenv=None):
+    def build_dist(self, qt_versions: List[QtVersion], disttype="local", pyenv=None, modtime=None):
         self._copy_licenses()
         if self._path_changelog.exists():
             self._copy_changelog()
@@ -111,7 +111,7 @@ class AddonBuilder:
         if self._callback_archive:
             self._callback_archive()

-        self._write_manifest(disttype)
+        self._write_manifest(disttype, modtime=modtime)

         ui_builder = UIBuilder(dist=PATH_DIST, config=self._config)

@@ -162,12 +162,13 @@ class AddonBuilder:

         return out_path

-    def _write_manifest(self, disttype):
+    def _write_manifest(self, disttype, modtime=None):
         ManifestUtils.generate_and_write_manifest(
             addon_properties=self._config,
             version=self._version,
             dist_type=disttype,
             target_dir=self._path_dist_module,
+            modtime=modtime,
         )

     def _copy_licenses(self):
diff --git a/aab/cli.py b/aab/cli.py
index 2ce6425..0956e98 100644
--- a/aab/cli.py
+++ b/aab/cli.py
@@ -89,7 +89,7 @@ def build(args):
     total = len(dists)
     for dist in dists:
         logging.info("\n=== Build task %s/%s ===", cnt, total)
-        builder.build(qt_versions=qt_versions, disttype=dist)
+        builder.build(qt_versions=qt_versions, disttype=dist, modtime=args.modtime)
         cnt += 1


@@ -146,7 +146,7 @@ def build_dist(args):
     total = len(dists)
     for dist in dists:
         logging.info("\n=== Build task %s/%s ===", cnt, total)
-        builder.build_dist(qt_versions=qt_versions, disttype=dist)
+        builder.build_dist(qt_versions=qt_versions, disttype=dist, modtime=args.modtime)
         cnt += 1


@@ -204,6 +204,12 @@ def construct_parser():
         default="local",
         choices=["local", "ankiweb", "all"],
     )
+    dist_parent.add_argument(
+        "--modtime",
+        help="Last modified timestamp",
+        type=int,
+        required=False,
+    )

     build_parent = argparse.ArgumentParser(add_help=False)
     build_parent.add_argument(
diff --git a/aab/manifest.py b/aab/manifest.py
index fc0038d..355e370 100644
--- a/aab/manifest.py
+++ b/aab/manifest.py
@@ -49,10 +49,11 @@ class ManifestUtils:
         version: str,
         dist_type: DistType,
         target_dir: Path,
+        modtime=None,
     ):
         logging.info("Writing manifest...")
         manifest = cls.generate_manifest_from_properties(
-            addon_properties=addon_properties, version=version, dist_type=dist_type
+            addon_properties=addon_properties, version=version, dist_type=dist_type, modtime=modtime
         )
         cls.write_manifest(manifest=manifest, target_dir=target_dir)

@@ -62,6 +63,7 @@ class ManifestUtils:
         addon_properties: Config,
         version: str,
         dist_type: DistType,
+        modtime=None,
     ) -> Dict[str, Any]:
         manifest = {
             "name": addon_properties["display_name"],
@@ -71,7 +73,7 @@ class ManifestUtils:
             "version": version,
             "homepage": addon_properties.get("homepage", ""),
             "conflicts": deepcopy(addon_properties["conflicts"]),
-            "mod": Git().modtime(version),
+            "mod": modtime if modtime is not None else Git().modtime(version),
         }

         # Add version specifiers: