diff --git a/poetry.lock b/poetry.lock
index 63b80db..54c41fc 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 2.3.4 and should not be changed by hand.
+# This file is automatically @generated by Poetry 2.5.1 and should not be changed by hand.
 
 [[package]]
 name = "anyio"
@@ -377,18 +377,19 @@ testing = ["fields", "hunter", "process-tests", "pytest-xdist", "virtualenv"]
 
 [[package]]
 name = "python-dateutil"
-version = "2.9.0.post0"
+version = "3.0.0"
 description = "Extensions to the standard Python datetime module"
 optional = false
 python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,>=2.7"
 groups = ["main"]
 files = [
-    {file = "python-dateutil-2.9.0.post0.tar.gz", hash = "sha256:37dd54208da7e1cd875388217d5e00ebd4179249f90fb72437e91a35459a0ad3"},
-    {file = "python_dateutil-2.9.0.post0-py2.py3-none-any.whl", hash = "sha256:a8b2bc7bffae282281c8140a97d3aa9c14da0b136dfe83f850eea9a5f7470427"},
+    {file = "python_dateutil-3.0.0-py2.py3-none-any.whl", hash = "sha256:3c79630202e4152c6add678446984236efe4f57e84d8e892aab0637bab82e9fd"},
+    {file = "python_dateutil-3.0.0.tar.gz", hash = "sha256:7ebcb3c29a92f3ceafe79a7a48a5c45677e9e004bbeec5742ac0bbb00560b7a2"},
 ]
 
 [package.dependencies]
-six = ">=1.5"
+six = ">=1.6"
+tzdata = "*"
 
 [[package]]
 name = "respx"
@@ -436,7 +437,7 @@ description = "A lil' TOML parser"
 optional = false
 python-versions = ">=3.8"
 groups = ["dev"]
-markers = "python_full_version <= \"3.11.0a6\""
+markers = "python_version == \"3.10\""
 files = [
     {file = "tomli-2.2.1-cp311-cp311-macosx_10_9_x86_64.whl", hash = "sha256:678e4fa69e4575eb77d103de3df8a895e1591b48e740211bd1067378c69e8249"},
     {file = "tomli-2.2.1-cp311-cp311-macosx_11_0_arm64.whl", hash = "sha256:023aa114dd824ade0100497eb2318602af309e5a55595f76b626d6d9f3b7b0a6"},
@@ -485,7 +486,19 @@ files = [
     {file = "typing_extensions-4.15.0.tar.gz", hash = "sha256:0cea48d173cc12fa28ecabc3b837ea3cf6f38c6d1136f85cbaaf598984861466"},
 ]
 
+[[package]]
+name = "tzdata"
+version = "2026.6"
+description = "Provider of IANA time zone data"
+optional = false
+python-versions = ">=2"
+groups = ["main"]
+files = [
+    {file = "tzdata-2026.6-py2.py3-none-any.whl", hash = "sha256:0a10eec6e13ef16b627fabed9a5f2ba61a62b1c67f327305f4e7e412a70b4aec"},
+    {file = "tzdata-2026.6.tar.gz", hash = "sha256:85d2cd9c09f81f0bb29db27759fc83af4f1e620efb814f8c5bf8b4cc4feece6d"},
+]
+
 [metadata]
 lock-version = "2.1"
 python-versions = "^3.10"
-content-hash = "b22ef64a460a272f2f4c7f4a2641db94c0695049cd77d5debc0416d8e39d155c"
+content-hash = "27d15d71686e88dd1c7b0802c8bfedf354a6dd6d51bb14707b3365dbf4ac269f"
diff --git a/pyproject.toml b/pyproject.toml
index 729a46a..f08afe0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,7 +13,7 @@ repository = "https://github.com/1Password/connect-sdk-python"
 
 [tool.poetry.dependencies]
 python = "^3.10"
-python-dateutil = "^2.8.1"
+python-dateutil = ">=2.8.1,<4.0.0"
 httpx = "^0.28.1"
 certifi = ">=2026.10.19"