diff --git a/eyecite/utils.py b/eyecite/utils.py
index b642d23..b2bb66a 100644
--- a/eyecite/utils.py
+++ b/eyecite/utils.py
@@ -122,7 +122,8 @@ def hash_sha256(dictionary: dict) -> int:
     """
 
     # Convert the dictionary to a JSON string
-    json_str: str = json.dumps(dictionary, sort_keys=True)
+    # default needed because of dates
+    json_str: str = json.dumps(dictionary, sort_keys=True, default=str)
 
     # Convert the JSON string to bytes
     json_bytes: bytes = json_str.encode("utf-8")
diff --git a/tests/test_ResolveTest.py b/tests/test_ResolveTest.py
index 8461ba7..61c4898 100644
--- a/tests/test_ResolveTest.py
+++ b/tests/test_ResolveTest.py
@@ -104,6 +104,9 @@ def checkResolution(
 
         self.assertResolution(citations, expected_resolution_dict)
 
+    def test_issue_167(self):
+        self.checkResolution((0, "25 Texas L.Rev. 199"))
+
     def test_full_resolution(self):
         # Test resolving a single, full citation
         self.checkResolution(