diff --git a/poetry.lock b/poetry.lock
index f2b0dcb5..f51e90dd 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -77,6 +77,17 @@ category = "dev"
 optional = false
 python-versions = "*"
 
+[[package]]
+name = "backports.zoneinfo"
+version = "0.2.1"
+description = "Backport of the standard library zoneinfo module"
+category = "main"
+optional = false
+python-versions = ">=3.6"
+
+[package.extras]
+tzdata = ["tzdata"]
+
 [[package]]
 name = "behave"
 version = "1.2.6"
@@ -842,16 +853,28 @@ category = "main"
 optional = false
 python-versions = "*"
 
+[[package]]
+name = "tzdata"
+version = "2021.1"
+description = "Provider of IANA time zone data"
+category = "main"
+optional = false
+python-versions = ">=2"
+
 [[package]]
 name = "tzlocal"
-version = "2.1"
+version = "3.0"
 description = "tzinfo object for the local timezone"
 category = "main"
 optional = false
-python-versions = "*"
+python-versions = ">=3.6"
 
 [package.dependencies]
-pytz = "*"
+"backports.zoneinfo" = {version = "*", markers = "python_version < \"3.9\""}
+tzdata = {version = "*", markers = "platform_system == \"Windows\""}
+
+[package.extras]
+test = ["pytest-mock (>=3.3)", "pytest (>=4.3)"]
 
 [[package]]
 name = "watchdog"
@@ -915,7 +938,7 @@ testing = ["behave", "pytest", "pytest-bdd", "toml"]
 [metadata]
 lock-version = "1.1"
 python-versions = ">=3.7.0, <3.11"
-content-hash = "c4f943f3dbd96f5aab8ad0ef2f3d3f6a7096dc75ea7d3e449949695d340208fb"
+content-hash = "9d78efa6bf5a3c0ed7476dcfa0381bca4400f1ef64462c787b8b4950d1128844"
 
 [metadata.files]
 ansiwrap = [
@@ -949,6 +972,24 @@ backcall = [
     {file = "backcall-0.2.0-py2.py3-none-any.whl", hash = "sha256:fbbce6a29f263178a1f7915c1940bde0ec2b2a967566fe1c65c1dfb7422bd255"},
     {file = "backcall-0.2.0.tar.gz", hash = "sha256:5cbdbf27be5e7cfadb448baf0aa95508f91f2bbc6c6437cd9cd06e2a4c215e1e"},
 ]
+"backports.zoneinfo" = [
+    {file = "backports.zoneinfo-0.2.1-cp36-cp36m-macosx_10_14_x86_64.whl", hash = "sha256:da6013fd84a690242c310d77ddb8441a559e9cb3d3d59ebac9aca1a57b2e18bc"},
+    {file = "backports.zoneinfo-0.2.1-cp36-cp36m-manylinux1_i686.whl", hash = "sha256:89a48c0d158a3cc3f654da4c2de1ceba85263fafb861b98b59040a5086259722"},
+    {file = "backports.zoneinfo-0.2.1-cp36-cp36m-manylinux1_x86_64.whl", hash = "sha256:1c5742112073a563c81f786e77514969acb58649bcdf6cdf0b4ed31a348d4546"},
+    {file = "backports.zoneinfo-0.2.1-cp36-cp36m-win32.whl", hash = "sha256:e8236383a20872c0cdf5a62b554b27538db7fa1bbec52429d8d106effbaeca08"},
+    {file = "backports.zoneinfo-0.2.1-cp36-cp36m-win_amd64.whl", hash = "sha256:8439c030a11780786a2002261569bdf362264f605dfa4d65090b64b05c9f79a7"},
+    {file = "backports.zoneinfo-0.2.1-cp37-cp37m-macosx_10_14_x86_64.whl", hash = "sha256:f04e857b59d9d1ccc39ce2da1021d196e47234873820cbeaad210724b1ee28ac"},
+    {file = "backports.zoneinfo-0.2.1-cp37-cp37m-manylinux1_i686.whl", hash = "sha256:17746bd546106fa389c51dbea67c8b7c8f0d14b5526a579ca6ccf5ed72c526cf"},
+    {file = "backports.zoneinfo-0.2.1-cp37-cp37m-manylinux1_x86_64.whl", hash = "sha256:5c144945a7752ca544b4b78c8c41544cdfaf9786f25fe5ffb10e838e19a27570"},
+    {file = "backports.zoneinfo-0.2.1-cp37-cp37m-win32.whl", hash = "sha256:e55b384612d93be96506932a786bbcde5a2db7a9e6a4bb4bffe8b733f5b9036b"},
+    {file = "backports.zoneinfo-0.2.1-cp37-cp37m-win_amd64.whl", hash = "sha256:a76b38c52400b762e48131494ba26be363491ac4f9a04c1b7e92483d169f6582"},
+    {file = "backports.zoneinfo-0.2.1-cp38-cp38-macosx_10_14_x86_64.whl", hash = "sha256:8961c0f32cd0336fb8e8ead11a1f8cd99ec07145ec2931122faaac1c8f7fd987"},
+    {file = "backports.zoneinfo-0.2.1-cp38-cp38-manylinux1_i686.whl", hash = "sha256:e81b76cace8eda1fca50e345242ba977f9be6ae3945af8d46326d776b4cf78d1"},
+    {file = "backports.zoneinfo-0.2.1-cp38-cp38-manylinux1_x86_64.whl", hash = "sha256:7b0a64cda4145548fed9efc10322770f929b944ce5cee6c0dfe0c87bf4c0c8c9"},
+    {file = "backports.zoneinfo-0.2.1-cp38-cp38-win32.whl", hash = "sha256:1b13e654a55cd45672cb54ed12148cd33628f672548f373963b0bff67b217328"},
+    {file = "backports.zoneinfo-0.2.1-cp38-cp38-win_amd64.whl", hash = "sha256:4a0f800587060bf8880f954dbef70de6c11bbe59c673c3d818921f042f9954a6"},
+    {file = "backports.zoneinfo-0.2.1.tar.gz", hash = "sha256:fadbfe37f74051d024037f223b8e001611eac868b5c5b06144ef4d8b799862f2"},
+]
 behave = [
     {file = "behave-1.2.6-py2.py3-none-any.whl", hash = "sha256:ebda1a6c9e5bfe95c5f9f0a2794e01c7098b3dde86c10a95d8621c5907ff6f1c"},
     {file = "behave-1.2.6.tar.gz", hash = "sha256:b9662327aa53294c1351b0a9c369093ccec1d21026f050c3bd9b3e5cccf81a86"},
@@ -1426,9 +1467,13 @@ typing-extensions = [
     {file = "typing_extensions-3.10.0.0-py3-none-any.whl", hash = "sha256:779383f6086d90c99ae41cf0ff39aac8a7937a9283ce0a414e5dd782f4c94a84"},
     {file = "typing_extensions-3.10.0.0.tar.gz", hash = "sha256:50b6f157849174217d0656f99dc82fe932884fb250826c18350e159ec6cdf342"},
 ]
+tzdata = [
+    {file = "tzdata-2021.1-py2.py3-none-any.whl", hash = "sha256:9ad21eada54c97001e3e9858a674b3ee6bebe4a4fb2b58465930f2af0ba6c85d"},
+    {file = "tzdata-2021.1.tar.gz", hash = "sha256:e19c7351f887522a1ac739d21041e592ddde6dd1b764fdefa8f7b2b3551d3d38"},
+]
 tzlocal = [
-    {file = "tzlocal-2.1-py2.py3-none-any.whl", hash = "sha256:e2cb6c6b5b604af38597403e9852872d7f534962ae2954c7f35efcb1ccacf4a4"},
-    {file = "tzlocal-2.1.tar.gz", hash = "sha256:643c97c5294aedc737780a49d9df30889321cbe1204eac2c2ec6134035a92e44"},
+    {file = "tzlocal-3.0-py3-none-any.whl", hash = "sha256:c736f2540713deb5938d789ca7c3fc25391e9a20803f05b60ec64987cf086559"},
+    {file = "tzlocal-3.0.tar.gz", hash = "sha256:f4e6e36db50499e0d92f79b67361041f048e2609d166e93456b50746dc4aef12"},
 ]
 watchdog = [
     {file = "watchdog-2.1.3-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:9628f3f85375a17614a2ab5eac7665f7f7be8b6b0a2a228e6f6a2e91dd4bfe26"},
diff --git a/pyproject.toml b/pyproject.toml
index feaf897d..8a7db22f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,7 +41,7 @@ pyyaml = ">=5.1"
 
 # dayone-only deps
 pytz = ">=2020"          # https://pythonhosted.org/pytz/#issues-limitations
-tzlocal = ">2.0, <3.0"   # https://github.com/regebro/tzlocal/blob/master/CHANGES.txt
+tzlocal = ">2.0,<4.0"   # https://github.com/regebro/tzlocal/blob/master/CHANGES.txt
 
 # Minimal deps required for testing
 # I don't like repeating deps here, but