diff --git a/src/pendulum/parsing/iso8601.py b/src/pendulum/parsing/iso8601.py
index c65d249e5..b57bc63a8 100644
--- a/src/pendulum/parsing/iso8601.py
+++ b/src/pendulum/parsing/iso8601.py
@@ -447,7 +447,9 @@ def _get_iso_8601_week(
         year += 1
 
     fmt = "%Y-%j"
-    string = f"{year}-{ordinal}"
+    # %Y requires a zero-padded 4-digit year in strptime, so years < 1000
+    # must be padded or the lookup fails.
+    string = f"{year:04d}-{ordinal}"
 
     dt = datetime.datetime.strptime(string, fmt)
 
diff --git a/tests/parsing/test_parse_iso8601.py b/tests/parsing/test_parse_iso8601.py
index ed2d39887..636fc875b 100644
--- a/tests/parsing/test_parse_iso8601.py
+++ b/tests/parsing/test_parse_iso8601.py
@@ -29,6 +29,12 @@
         ("2008-W39-6", date(2008, 9, 27)),
         ("2009-W53-7", date(2010, 1, 3)),
         ("2009-W01-1", date(2008, 12, 29)),
+        # Week date with a year < 1000 (%Y in strptime needs the padding)
+        ("0999-W34-6", date(999, 8, 24)),
+        ("0416-W34-6", date(416, 8, 27)),
+        ("0004-W10-5", date(4, 3, 5)),
+        ("0416W346", date(416, 8, 27)),
+        ("0416-W34", date(416, 8, 22)),
         # Time
         ("12:34", time(12, 34, 0)),
         ("12:34:56", time(12, 34, 56)),