diff --git a/src/common/dates.py b/src/common/dates.py
index c599abb2..3ceb0384 100644
--- a/src/common/dates.py
+++ b/src/common/dates.py
@@ -112,6 +112,10 @@ def today_at_midnight() -> datetime.datetime:
     """Create a datetime object with today's date, at midnight."""
     return datetime.datetime.now(tz=datetime.timezone.utc).replace(hour=0, minute=0, second=0, microsecond=0)
 
+def today_at_end_of_day() -> datetime.datetime:
+    """Create a datetime object with today's date, at the end of the day."""
+    return datetime.datetime.now(tz=datetime.timezone.utc).replace(hour=23, minute=59, second=59, microsecond=999999)
+
 def today() -> datetime.date:
     """Create a date object with today's date."""
     return datetime.datetime.now(tz=datetime.timezone.utc).date()
diff --git a/src/common/releasedata.py b/src/common/releasedata.py
index 5c061696..02784198 100644
--- a/src/common/releasedata.py
+++ b/src/common/releasedata.py
@@ -7,7 +7,7 @@ from pathlib import Path
 from types import TracebackType
 from typing import Optional, Type
 
-from . import endoflife
+from . import dates, endoflife
 
 SRC_DIR = Path('src')
 DATA_DIR = Path('releases')
@@ -182,6 +182,10 @@ class ProductData:
 
     def declare_version(self, version_name: str, versions_date: datetime) -> None:
         self.updated = True
+        if versions_date > dates.today_at_end_of_day():
+            logging.warning(f"skipping declaration of version {version_name} with future date {versions_date} for {self}")
+            return
+
         if version_name in self.versions and self.versions[version_name].date() != versions_date:
             logging.info(f"overwriting {version_name} ({self.get_version(version_name).date()} -> {versions_date}) for {self}")
             self.versions[version_name].replace_date(versions_date)