diff --git a/src/scriv/collect.py b/src/scriv/collect.py
index 98df478..1d05835 100644
--- a/src/scriv/collect.py
+++ b/src/scriv/collect.py
@@ -71,6 +71,12 @@ def collect(
                 if etitle is None:
                     continue
                 eversion = Version.from_text(etitle)
+                if eversion is None:
+                    sys.exit(
+                        f"Entry {etitle!r} is not a valid version! "
+                        + "If scriv should ignore this heading, add "
+                        + "'scriv-end-here' somewhere before it."
+                    )
                 if eversion == version:
                     sys.exit(
                         f"Entry {etitle!r} already uses "