diff --git a/incorporealcms/pages.py b/incorporealcms/pages.py
index 1fc2f61..26e3734 100644
--- a/incorporealcms/pages.py
+++ b/incorporealcms/pages.py
@@ -7,7 +7,6 @@ import re
 from flask import Blueprint, Markup, abort
 from flask import current_app as app
 from flask import redirect, request, send_from_directory
-from tzlocal import get_localzone
 
 from incorporealcms.lib import get_meta_str, init_md, render
 
@@ -51,7 +50,7 @@ def handle_markdown_file_path(resolved_path):
     try:
         logger.debug("opening resolved path '%s'", resolved_path)
         with app.open_instance_resource(resolved_path, 'r') as entry_file:
-            mtime = datetime.datetime.fromtimestamp(os.path.getmtime(entry_file.name), get_localzone())
+            mtime = datetime.datetime.fromtimestamp(os.path.getmtime(entry_file.name), tz=datetime.timezone.utc)
             entry = entry_file.read()
         logger.debug("resolved path '%s' read", resolved_path)
     except OSError:
diff --git a/requirements/requirements-dev.txt b/requirements/requirements-dev.txt
index 1d66c90..848bfd2 100644
--- a/requirements/requirements-dev.txt
+++ b/requirements/requirements-dev.txt
@@ -116,8 +116,6 @@ pytest==7.1.1
     #   pytest-cov
 pytest-cov==3.0.0
     # via -r requirements/requirements-dev.in
-pytz-deprecation-shim==0.1.0.post0
-    # via tzlocal
 pyyaml==6.0
     # via
     #   bandit
@@ -154,10 +152,6 @@ tox==3.24.5
     #   tox-wheel
 tox-wheel==0.7.0
     # via -r requirements/requirements-dev.in
-tzdata==2022.1
-    # via pytz-deprecation-shim
-tzlocal==4.1
-    # via -r requirements/requirements.in
 urllib3==1.26.9
     # via requests
 versioneer==0.22
diff --git a/requirements/requirements.in b/requirements/requirements.in
index 2769af8..62ad2c6 100644
--- a/requirements/requirements.in
+++ b/requirements/requirements.in
@@ -1,3 +1,2 @@
 Flask                       # general purpose web service and web server stuff
 Markdown                    # markdown rendering in templates
-tzlocal                     # identifying system's local timezone
diff --git a/requirements/requirements.txt b/requirements/requirements.txt
index 9ee7f1a..3a78229 100644
--- a/requirements/requirements.txt
+++ b/requirements/requirements.txt
@@ -16,11 +16,5 @@ markdown==3.3.6
     # via -r requirements/requirements.in
 markupsafe==2.1.1
     # via jinja2
-pytz-deprecation-shim==0.1.0.post0
-    # via tzlocal
-tzdata==2022.1
-    # via pytz-deprecation-shim
-tzlocal==4.1
-    # via -r requirements/requirements.in
 werkzeug==2.0.3
     # via flask