diff --git a/src/pendulum/parsing/iso8601.py b/src/pendulum/parsing/iso8601.py
index c65d249e..699185a0 100644
--- a/src/pendulum/parsing/iso8601.py
+++ b/src/pendulum/parsing/iso8601.py
@@ -49,7 +49,7 @@
     # Subsecond part (optional)
     "    (?P<subsecondsection>"
     "        (?:[.,])"  # Subsecond separator (optional)
-    r"        (?P<subsecond>\d{1,9})"  # Subsecond
+    r"        (?P<subsecond>\d+)"  # Subsecond
     "    )?"
     # Timezone offset
     "    (?P<tz>"