diff --git a/tests/README.md b/tests/README.md
index 01b6b0af..e99222eb 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -1,8 +1,9 @@
 # Tests for osxphotos #
 
 ## Running Tests ##
-Tests require pytest:
+Tests require pytest and pytest-mock:
 `pip install pytest`
+`pip install pytest-mock`
 
 To run the tests, do the following from the main source folder:
 `python -m pytest tests/`
diff --git a/tests/test_catalina_10_15_1.py b/tests/test_catalina_10_15_1.py
index 8e2cc754..1b9bd907 100644
--- a/tests/test_catalina_10_15_1.py
+++ b/tests/test_catalina_10_15_1.py
@@ -106,17 +106,17 @@ def test_init4():
     except:
         pass
 
-
-def test_init5():
+def test_init5(mocker):
     # test failed get_last_library_path
     import osxphotos
-
+    
     def bad_library():
         return None
 
-    # force get_last_library to return a bad path for testing
-    osxphotos.photosdb.get_last_library_path = bad_library
-
+    # get_last_library actually in utils but need to patch it in photosdb because it's imported into photosdb
+    # as: from .utils import get_last_library
+    mocker.patch("osxphotos.photosdb.get_last_library_path", new=bad_library)
+    
     with pytest.raises(Exception):
         assert osxphotos.PhotosDB()
 
diff --git a/tests/test_catalina_10_15_4.py b/tests/test_catalina_10_15_4.py
index 2e076aa3..3645c749 100644
--- a/tests/test_catalina_10_15_4.py
+++ b/tests/test_catalina_10_15_4.py
@@ -107,19 +107,21 @@ def test_init4():
         pass
 
 
-def test_init5():
+def test_init5(mocker):
     # test failed get_last_library_path
     import osxphotos
-
+    
     def bad_library():
         return None
 
-    # force get_last_library to return a bad path for testing
-    osxphotos.photosdb.get_last_library_path = bad_library
-
+    # get_last_library actually in utils but need to patch it in photosdb because it's imported into photosdb
+    # as: from .utils import get_last_library
+    mocker.patch("osxphotos.photosdb.get_last_library_path", new=bad_library)
+    
     with pytest.raises(Exception):
         assert osxphotos.PhotosDB()
 
+
 def test_db_len():
     import osxphotos