diff --git a/requirements-dev.txt b/requirements-dev.txt
index eda4a30..4cb8b55 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -121,7 +121,7 @@ typing-extensions==4.16.0
     # via
     #   mypy
     #   pyuspto
-tzdata==2026.3
+tzdata==2026.4
     # via
     #   pyUSPTO (pyproject.toml)
     #   pyuspto
diff --git a/requirements.txt b/requirements.txt
index b2ccbeb..5644e11 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,7 +12,7 @@ idna==3.19
     # via requests
 requests==2.34.2
     # via pyUSPTO (pyproject.toml)
-tzdata==2026.3
+tzdata==2026.4
     # via pyUSPTO (pyproject.toml)
 urllib3==2.7.0
     # via