diff --git a/bookwyrm/tests/test_sealed_date.py b/bookwyrm/tests/test_sealed_date.py
index c01625078..af46519a9 100644
--- a/bookwyrm/tests/test_sealed_date.py
+++ b/bookwyrm/tests/test_sealed_date.py
@@ -14,14 +14,14 @@ class SealedDateTest(unittest.TestCase):
     def test_day_seal(self):
         sealed = sealed_date.SealedDate.from_datetime(self.dt)
         self.assertEqual(self.dt, sealed)
-        self.assertEqual("2023-10-20", str(sealed))
+        self.assertEqual("2023-10-20", sealed.partial_isoformat())
 
     def test_month_seal(self):
         sealed = sealed_date.MonthSeal.from_datetime(self.dt)
         self.assertEqual(self.dt, sealed)
-        self.assertEqual("2023-10", str(sealed))
+        self.assertEqual("2023-10", sealed.partial_isoformat())
 
     def test_year_seal(self):
         sealed = sealed_date.YearSeal.from_datetime(self.dt)
         self.assertEqual(self.dt, sealed)
-        self.assertEqual("2023", str(sealed))
+        self.assertEqual("2023", sealed.partial_isoformat())
diff --git a/bookwyrm/utils/sealed_date.py b/bookwyrm/utils/sealed_date.py
index 18a0bea68..6b3994bbb 100644
--- a/bookwyrm/utils/sealed_date.py
+++ b/bookwyrm/utils/sealed_date.py
@@ -12,7 +12,7 @@ class SealedDate(datetime):  # TODO: migrate from DateTimeField to DateField
     def has_month(self) -> bool:
         return True
 
-    def __str__(self):
+    def partial_isoformat(self) -> str:
         return self.strftime("%Y-%m-%d")
 
     @classmethod
@@ -26,7 +26,7 @@ class MonthSeal(SealedDate):
     def has_day(self) -> bool:
         return False
 
-    def __str__(self):
+    def partial_isoformat(self) -> str:
         return self.strftime("%Y-%m")
 
 
@@ -35,5 +35,5 @@ class YearSeal(SealedDate):
     def has_month(self) -> bool:
         return False
 
-    def __str__(self):
+    def partial_isoformat(self) -> str:
         return self.strftime("%Y")