diff --git a/app/__init__.py b/app/__init__.py
index 8183374..0eb4e78 100644
--- a/app/__init__.py
+++ b/app/__init__.py
@@ -10,6 +10,7 @@ from .constants import (
     SIG_BANNED_TAGS, STRICT_BANNED_TAGS,
     )
 from .lib.babycode import babycode_to_html, babycode_to_rssxml, EMOJI, BABYCODE_VERSION
+from .lib.exceptions import SiteNameMissingException
 from datetime import datetime, timezone
 from flask_caching import Cache
 import os
@@ -165,6 +166,8 @@ def create_app():
         load_dotenv()
     else:
         app.config["DB_PATH"] = "data/db/db.prod.sqlite"
+        if not app.config["SERVER_NAME"]:
+            raise SiteNameMissingException()
 
     app.config["SECRET_KEY"] = os.getenv("FLASK_SECRET_KEY")
 
diff --git a/app/lib/babycode.py b/app/lib/babycode.py
index 36663fa..e760aac 100644
--- a/app/lib/babycode.py
+++ b/app/lib/babycode.py
@@ -196,13 +196,12 @@ class RSSXMLRenderer(BabycodeRenderer):
 
     def make_mention(self, e):
         from ..models import Users
-        from flask import url_for, current_app
-        with current_app.test_request_context('/'):
-            target_user = Users.find({'username': e['name'].lower()})
-            if not target_user:
-                return f"@{e['name']}"
+        from flask import url_for
+        target_user = Users.find({'username': e['name'].lower()})
+        if not target_user:
+            return f"@{e['name']}"
 
-            return f'<a href="{url_for('users.page', username=target_user.username, _external=True)}" title="@{target_user.username}">{target_user.get_readable_name()}</a>'
+        return f'<a href="{url_for('users.page', username=target_user.username, _external=True)}" title="@{target_user.username}">{'@' if not target_user.has_display_name() else ''}{target_user.get_readable_name()}</a>'
 
 
 NAMED_COLORS = [
diff --git a/app/lib/exceptions.py b/app/lib/exceptions.py
new file mode 100644
index 0000000..7123d7d
--- /dev/null
+++ b/app/lib/exceptions.py
@@ -0,0 +1,9 @@
+class MissingConfigurationException(Exception):
+    def __init__(self, configuration_field: str):
+        message = f"Missing configuration field '{configuration_field}'"
+        super().__init__(message)
+
+
+class SiteNameMissingException(MissingConfigurationException):
+    def __init__(self):
+        super().__init__('SITE_NAME')