diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index dfe78b6..d78c986 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -37,8 +37,8 @@ jobs:
         run: |
           pip install -r requirements/run.txt
           pip install -r requirements/test.txt
-#      - name: Run tests
-#        run: pytest tests/ --cov=Semi_ATE
+      - name: Run tests
+        run: pytest tests/ --cov=Semi_ATE
       - name: Create package
         run: python setup.py sdist
       - name: Check package
diff --git a/Semi_ATE/TnD/TnD.py b/Semi_ATE/TnD/TnD.py
index e3eb4fd..73463f3 100644
--- a/Semi_ATE/TnD/TnD.py
+++ b/Semi_ATE/TnD/TnD.py
@@ -10,6 +10,7 @@
 import datetime
 import os
 import time
+import platform
 
 
 def is_date(stamp):
@@ -233,6 +234,7 @@ def __init__(self, stamp=None):
         loct = int(time.time())
         self.tz = (time.mktime(time.gmtime(loct)) - loct) / 3600
         self.dst = time.localtime()[8]
+        self.os = platform.system()
         self.__call__(stamp)
 
     def __call__(self, stamp=None):
@@ -276,6 +278,8 @@ def __call__(self, stamp=None):
         self._populate()
 
     def _populate(self):
+        if self.os == "Windows" and self.epoch < -43200:
+            raise DTError("Windows doesn't support negative epoch times beyond -43200 (12 hours prior)")
         t = time.gmtime(self.epoch)
         d = datetime.date(t.tm_year, t.tm_mon, t.tm_mday)
         self.datecode = "%4d%02d%1d" % (
diff --git a/requirements/test.txt b/requirements/test.txt
index 54eadce..d344c06 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -4,4 +4,3 @@ check-manifest
 pip 
 setuptools 
 twine
-tree
diff --git a/tests/test_DT.py b/tests/test_DT.py
index be92588..4bbb023 100644
--- a/tests/test_DT.py
+++ b/tests/test_DT.py
@@ -1,3 +1,5 @@
+import platform
+
 from Semi_ATE.TnD import DT, DTError
 
 
@@ -10,7 +12,16 @@ def test_init_int_pos():
 
 
 def test_init_int_neg():
-    assert DT(-7948800).epoch == -7948800
+    if platform.system() == "Windows":
+        try:
+            DT(-43201)
+        except DTError:
+            assert True
+        else:
+            assert False
+        assert DT(-43200).epoch == -43200
+    else:
+        assert DT(-7948800).epoch == -7948800
 
 
 def test_init_float_pos():
@@ -18,7 +29,16 @@ def test_init_float_pos():
 
 
 def test_init_float_neg():
-    assert DT(-7948800.663).epoch == -7948800
+    if platform.system() == "Windows":
+        try:
+            DT(-43201.0)
+        except DTError:
+            assert True
+        else:
+            assert False
+        assert DT(-43200.0).epoch == -43200
+    else:
+        assert DT(-7948800.663).epoch == -7948800
 
 
 def test_init_str_datecode_post_epoch():  # YYWWD
@@ -43,7 +63,15 @@ def test_init_str_date_post_epoch():  # DDMMYYYY
 
 
 def test_init_str_date_pre_epoch():
-    assert DT("01101969").date == "01101969"
+    if platform.system() == "Windows":
+        try:
+            DT("01101969")
+        except DTError:
+            assert True
+        else:
+            assert False
+    else:
+       assert DT("01101969").date == "01101969"
 
 
 def test_init_str_invalid():
@@ -236,7 +264,3 @@ def test__ge__():
 
 def test__str__():
     assert True
-
-
-def test_is_date_ok():
-    assert DT("01101969")