diff --git a/PFERD/ilias/date_demangler.py b/PFERD/ilias/date_demangler.py
index 048df70..9c1fc8d 100644
--- a/PFERD/ilias/date_demangler.py
+++ b/PFERD/ilias/date_demangler.py
@@ -24,12 +24,17 @@ def demangle_date(date: str) -> Optional[datetime.datetime]:
     """
     saved = locale.setlocale(locale.LC_ALL)
     try:
-        locale.setlocale(locale.LC_ALL, 'de_DE.UTF-8')
+        try:
+            locale.setlocale(locale.LC_ALL, 'de_DE.UTF-8')
+        except locale.Error:
+            PRETTY.warning(
+                "Could not set language to german. Assuming you use english everywhere."
+            )
 
         date = re.sub(r"\s+", " ", date)
-        date = date.replace("Gestern", _yesterday().strftime("%d. %b %Y"))
-        date = date.replace("Heute", datetime.date.today().strftime("%d. %b %Y"))
-        date = date.replace("Morgen", _tomorrow().strftime("%d. %b %Y"))
+        date = re.sub("Gestern|Yesterday", _yesterday().strftime("%d. %b %Y"), date, re.I)
+        date = re.sub("Heute|Today", datetime.date.today().strftime("%d. %b %Y"), date, re.I)
+        date = re.sub("Morgen|Tomorrow", _tomorrow().strftime("%d. %b %Y"), date, re.I)
         return datetime.datetime.strptime(date, "%d. %b %Y, %H:%M")
     except ValueError:
         PRETTY.warning(f"Could not parse date {date!r}")