diff --git a/tests/utils.py b/tests/utils.py
index f9e54c09d..48bb5edad 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -8,6 +8,8 @@
    python -m unittest tests.utils.TestTicker
 
 """
+from unittest import TestSuite
+
 # import pandas as pd
 # import numpy as np
 
@@ -34,16 +36,16 @@ def test_storeTzNoRaise(self):
         tkr = 'AMZN'
         tz1 = "America/New_York"
         tz2 = "London/Europe"
-        cache = yf.utils.get_tz_cache()
+        cache = yf.cache.get_tz_cache()
         cache.store(tkr, tz1)
         cache.store(tkr, tz2)
 
     def test_setTzCacheLocation(self):
-        self.assertEqual(yf.utils._DBManager.get_location(), self.tempCacheDir.name)
+        self.assertEqual(yf.cache._TzDBManager.get_location(), self.tempCacheDir.name)
 
         tkr = 'AMZN'
         tz1 = "America/New_York"
-        cache = yf.utils.get_tz_cache()
+        cache = yf.cache.get_tz_cache()
         cache.store(tkr, tz1)
 
         self.assertTrue(os.path.exists(os.path.join(self.tempCacheDir.name, "tkr-tz.db")))
@@ -60,10 +62,10 @@ def test_tzCacheRootStore(self):
         tz1 = "America/New_York"
 
         # During attempt to store, will discover cannot write
-        yf.utils.get_tz_cache().store(tkr, tz1)
+        yf.cache.get_tz_cache().store(tkr, tz1)
 
         # Handling the store failure replaces cache with a dummy
-        cache = yf.utils.get_tz_cache()
+        cache = yf.cache.get_tz_cache()
         self.assertTrue(cache.dummy)
         cache.store(tkr, tz1)
 
@@ -71,19 +73,19 @@ def test_tzCacheRootLookup(self):
         # Test that if cache path in read-only filesystem, no exception.
         tkr = 'AMZN'
         # During attempt to lookup, will discover cannot write
-        yf.utils.get_tz_cache().lookup(tkr)
+        yf.cache.get_tz_cache().lookup(tkr)
 
         # Handling the lookup failure replaces cache with a dummy
-        cache = yf.utils.get_tz_cache()
+        cache = yf.cache.get_tz_cache()
         self.assertTrue(cache.dummy)
         cache.lookup(tkr)
 
 
 def suite():
-    suite = unittest.TestSuite()
-    suite.addTest(TestCache('Test cache'))
-    suite.addTest(TestCacheNoPermission('Test cache no permission'))
-    return suite
+    ts: TestSuite = unittest.TestSuite()
+    ts.addTest(TestCache('Test cache'))
+    ts.addTest(TestCacheNoPermission('Test cache no permission'))
+    return ts
 
 
 if __name__ == '__main__':
diff --git a/yfinance/utils.py b/yfinance/utils.py
index 53eac44a9..90d70136b 100644
--- a/yfinance/utils.py
+++ b/yfinance/utils.py
@@ -772,7 +772,7 @@ def fix_Yahoo_dst_issue(df, interval):
         f_pre_midnight = (df.index.minute == 0) & (df.index.hour.isin([22, 23]))
         dst_error_hours = _np.array([0] * df.shape[0])
         dst_error_hours[f_pre_midnight] = 24 - df.index[f_pre_midnight].hour
-        df.index += _pd.TimedeltaIndex(dst_error_hours, 'h')
+        df.index += _pd.to_timedelta(dst_error_hours, 'h')
     return df