diff --git a/stw_potsdam/swp_webspeiseplan_parser.py b/stw_potsdam/swp_webspeiseplan_parser.py
index a622ec6..95c1739 100644
--- a/stw_potsdam/swp_webspeiseplan_parser.py
+++ b/stw_potsdam/swp_webspeiseplan_parser.py
@@ -1,7 +1,7 @@
 import logging
 from datetime import datetime, date
 from stw_potsdam.xml_types.canteen_xml import CanteenMeta, CanteenXML
-from stw_potsdam.xml_types.times_xml import TimesXML
+from stw_potsdam.xml_types.times_xml import CanteenOpenTimespec, TimesXML
 from stw_potsdam.xml_types.meal_xml import MealXML
 
 
@@ -38,23 +38,21 @@ class SWPWebspeiseplanParser:
             )
         canteen_meta = CanteenMeta(**meta)
         weekday_dict = {
-            "monday": f"{outlet['moZeit1']}, {outlet['moZeit2']}",
-            "tuesday": f"{outlet['diZeit1']}, {outlet['diZeit2']}",
-            "wednesday": f"{outlet['miZeit1']}, {outlet['miZeit2']}",
-            "thursday": f"{outlet['doZeit1']}, {outlet['doZeit2']}",
-            "friday": f"{outlet['frZeit1']}, {outlet['frZeit2']}",
-            "saturday": f"{outlet['saZeit1']}, {outlet['saZeit2']}",
-            "sunday": f"{outlet['soZeit1']}, {outlet['soZeit2']}",
+            # this approach only lists the first (valid) opening time,
+            # since OpenMensa does not support multiple time specs
+            # (yet).
+            "monday": outlet['moZeit1'] or outlet['moZeit2'],
+            "tuesday": outlet['diZeit1'] or outlet['diZeit2'],
+            "wednesday": outlet['miZeit1'] or outlet['miZeit2'],
+            "thursday": outlet['doZeit1'] or outlet['doZeit2'],
+            "friday": outlet['frZeit1'] or outlet['frZeit2'],
+            "saturday": outlet['saZeit1'] or outlet['saZeit2'],
+            "sunday": outlet['soZeit1'] or outlet['soZeit2'],
         }
 
-        weekday_dict = {
-            k: v.replace("None, None", "")
-            .replace("None,", "")
-            .replace(", None", "")
-            for k, v in weekday_dict.items()
-        }
-
-        canteen_times = TimesXML(weekday_dict)
+        canteen_times = TimesXML({
+            k: CanteenOpenTimespec(v) for k, v in weekday_dict.items()
+        })
         canteen = CanteenXML(canteen_meta, canteen_times)
         return canteen
 
diff --git a/stw_potsdam/xml_types/times_xml.py b/stw_potsdam/xml_types/times_xml.py
index 210034c..a458d13 100644
--- a/stw_potsdam/xml_types/times_xml.py
+++ b/stw_potsdam/xml_types/times_xml.py
@@ -1,11 +1,60 @@
+import re
+
 from dataclasses import dataclass
 from xml.dom import minidom
 
 
+class CanteenOpenTimespec(str):
+    """Represents valid daily opening times in openMensaFeedv2."""
+
+    CLOSED = "geschlossen"
+    CLOSED_VALID_VALUES = {
+        CLOSED,
+        None,
+        False,
+        "",
+    }
+
+    PATTERN = (r'.*(?P<hour1>\d{1,2}):(?P<min1>\d{1,2})\s*'
+               r'-\s*(?P<hour2>\d{1,2}):(?P<min2>\d{1,2}).*')
+    MATCHER = re.compile(PATTERN)
+
+    def __new__(cls, spec):
+        """Create CanteenOpenTimespec object.
+
+        Args:
+            spec (str | bool | None): time specification
+        """
+        if spec in cls.CLOSED_VALID_VALUES:
+            return super().__new__(cls, cls.CLOSED)
+
+        match = cls.MATCHER.match(str(spec))
+        if not match:
+            raise ValueError(f'Invalid time specification: {spec!r} does'
+                             f' not conform to regex {cls.PATTERN!r}')
+        # parse to int for format zerofill
+        int_spec = {k: int(v) for k, v in match.groupdict().items()}
+        clean_spec = (
+            f'{int_spec["hour1"]:02}:{int_spec["min1"]:02}-'
+            f'{int_spec["hour2"]:02}:{int_spec["min2"]:02}'
+        )
+        return super().__new__(cls, clean_spec)
+
+
 @dataclass
 class TimesXML:
     """Represents the times tag in openMensaFeedv2."""
 
+    VALID_DAYS = (
+        "monday",
+        "tuesday",
+        "wednesday",
+        "thursday",
+        "friday",
+        "saturday",
+        "sunday",
+    )
+
     monday: str
     tuesday: str
     wednesday: str
@@ -14,29 +63,24 @@ class TimesXML:
     saturday: str
     sunday: str
 
-    def __init__(self, weekday_dict: dict[str, str] = None):
+    def __init__(self, weekday_dict: dict[str, CanteenOpenTimespec] = None):
         """Init TimesXML object.
 
         Args:
             weekday_dict (dict[str, str]): _description_
         """
         for key in weekday_dict:
-            if key in (
-                "monday",
-                "tuesday",
-                "wednesday",
-                "thursday",
-                "friday",
-                "saturday",
-                "sunday",
-            ):
+            if key in self.VALID_DAYS:
                 setattr(self, key, weekday_dict[key])
             else:
                 raise KeyError()
 
-    def __create_node(self, doc: minidom.Document, tag: str, value: str):
+    def __create_node(self,
+                      doc: minidom.Document,
+                      tag: str,
+                      value: CanteenOpenTimespec):
         elem = doc.createElement(tag)
-        if value == "geschlossen":
+        if value in CanteenOpenTimespec.CLOSED_VALID_VALUES:
             elem.setAttribute("closed", "true")
         else:
             elem.setAttribute("open", value)
@@ -53,18 +97,9 @@ class TimesXML:
         """
         times = doc.createElement("times")
         times.setAttribute("type", "opening")
-        monday = self.__create_node(doc, "monday", self.monday)
-        times.appendChild(monday)
-        tuesday = self.__create_node(doc, "tuesday", self.tuesday)
-        times.appendChild(tuesday)
-        wednesday = self.__create_node(doc, "wednesday", self.wednesday)
-        times.appendChild(wednesday)
-        thursday = self.__create_node(doc, "thursday", self.thursday)
-        times.appendChild(thursday)
-        friday = self.__create_node(doc, "friday", self.friday)
-        times.appendChild(friday)
-        saturday = self.__create_node(doc, "saturday", self.saturday)
-        times.appendChild(saturday)
-        sunday = self.__create_node(doc, "sunday", self.sunday)
-        times.appendChild(sunday)
+
+        for day in self.VALID_DAYS:
+            day_node = self.__create_node(doc, day, getattr(self, day))
+            times.appendChild(day_node)
+
         return times