diff --git a/.github/workflows/action.yml b/.github/workflows/action.yml
index aa5fefd..04c3fea 100644
--- a/.github/workflows/action.yml
+++ b/.github/workflows/action.yml
@@ -6,9 +6,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
-        poetry-version: ["1.8.5"]
-        os: ["ubuntu-22.04", "macos-latest", "windows-latest"]
+        python-version: ["3.13"]
+        poetry-version: ["2.3.1"]
+        os: ["ubuntu-latest", "macos-latest", "windows-latest"]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
diff --git a/pyproject.toml b/pyproject.toml
index 2f57c5b..22315be 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,21 +11,16 @@ repository = "https://github.com/leakix/l9format-python"
 documentation = "https://github.com/leakix/l9format-python"
 
 [tool.poetry.dependencies]
-python = "^3.9"
-# Updating to 0.9.0 breaks the support of iso8601.
-# The author of serde updated its code to use the stdlib iso8601 support, which
-# does not support for instance:
-# 2023-10-05T23:30:36.823867784Z
-# Bump up to python 3.11 fixes the issue as it seems fixed in the stdlib of 3.11
-serde = "^0.8.1"
+python = "^3.13"
+serde = "^0.9.0"
 
 [tool.poetry.group.dev.dependencies]
-black = "^24.10.0"
-fire = "^0.7.0"
-isort = "^5.12.0"
-pip-audit = "^2.7.3"
-pytest = "^8.3.4"
-ruff = "^0.9.2"
+black = "^26.1.0"
+fire = "^0.7.1"
+isort = "^7.0.0"
+pip-audit = "^2.10.0"
+pytest = "^9.0.2"
+ruff = "^0.14.14"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]
diff --git a/tests/test_l9format.py b/tests/test_l9format.py
index 443ba80..6ce2e2a 100644
--- a/tests/test_l9format.py
+++ b/tests/test_l9format.py
@@ -21,3 +21,23 @@ def test_l9events_form_ip4scout():
     for path in IP4SCOUT_FILES:
         c = json.load(open(str(path), "r"))
         l9format.L9Event.from_dict(c)
+
+
+def test_iso8601_nanosecond_parsing():
+    """
+    Test ISO8601 datetime parsing with nanosecond precision.
+
+    serde 0.9.0+ uses Python stdlib iso8601 support which handles nanoseconds
+    correctly in Python 3.11+.
+    """
+    path = TESTS_DIR / "l9event.json"
+    c = json.load(open(str(path), "r"))
+    # Use a timestamp with nanosecond precision (9 decimal places)
+    c["time"] = "2023-10-05T23:30:36.823867784Z"
+    event = l9format.L9Event.from_dict(c)
+    assert event.time.year == 2023
+    assert event.time.month == 10
+    assert event.time.day == 5
+    assert event.time.hour == 23
+    assert event.time.minute == 30
+    assert event.time.second == 36