diff --git a/mellon/base_model.py b/mellon/base_model.py
index 5dcd292..b022b2f 100644
--- a/mellon/base_model.py
+++ b/mellon/base_model.py
@@ -127,6 +127,7 @@ def __repr__(self):
         L = object_str(self.L, ["cells", "ranks"])
         nn_distances = object_str(self.nn_distances, ["cells"])
         initial_value = object_str(self.initial_value, ["ranks"])
+        d = object_str(self.d, ["cells"])
         string = (
             f"{name}("
             f"\n    cov_func_curry={self.cov_func_curry},"
@@ -137,7 +138,7 @@ def __repr__(self):
             f"\n    optimizer={self.optimizer},"
             f"\n    landmarks={landmarks},"
             f"\n    nn_distances={nn_distances},"
-            f"\n    d={self.d},"
+            f"\n    d={d},"
             f"\n    mu={self.mu},"
             f"\n    ls={self.ls},"
             f"\n    ls_factor={self.ls_factor},"
diff --git a/mellon/base_predictor.py b/mellon/base_predictor.py
index 6c366f3..7aeeaca 100644
--- a/mellon/base_predictor.py
+++ b/mellon/base_predictor.py
@@ -19,6 +19,7 @@
     deserialize,
     ensure_2d,
     make_multi_time_argument,
+    object_str,
 )
 from .derivatives import (
     gradient,
@@ -121,8 +122,8 @@ def __repr__(self):
             + "and data:\n"
             + "\n".join(
                 [
-                    str(key) + ": " + repr(getattr(self, key))
-                    for key in self._data_dict().keys()
+                    str(key) + ": " + object_str(v)
+                    for key, v in self._data_dict().items()
                 ]
             )
         )
diff --git a/mellon/time_sensitive_density_estimator.py b/mellon/time_sensitive_density_estimator.py
index 25253ce..02e34c1 100644
--- a/mellon/time_sensitive_density_estimator.py
+++ b/mellon/time_sensitive_density_estimator.py
@@ -312,6 +312,7 @@ def __repr__(self):
         normalize_per_time_point = object_str(
             self.normalize_per_time_point, ["time points"]
         )
+        d = object_str(self.d, ["cells"])
         string = (
             f"{name}("
             f"\n    cov_func_curry={self.cov_func_curry},"
@@ -323,7 +324,7 @@ def __repr__(self):
             f"\n    landmarks={landmarks},"
             f"\n    nn_distances={nn_distances},"
             f"\n    normalize_per_time_point={normalize_per_time_point},"
-            f"\n    d={self.d},"
+            f"\n    d={d},"
             f"\n    mu={self.mu},"
             f"\n    ls={self.ls},"
             f"\n    ls_time={self.ls_time},"
diff --git a/tests/time_sensitive_density_estimator.py b/tests/time_sensitive_density_estimator.py
index 14a82d6..1b78471 100644
--- a/tests/time_sensitive_density_estimator.py
+++ b/tests/time_sensitive_density_estimator.py
@@ -241,7 +241,7 @@ def test_density_estimator_errors(common_setup_time_sensitive):
     est.fit_predict()
     est.predict.n_obs = None
     with pytest.raises(ValueError):
-        est.predict(X, normalize=True)
+        est.predict(X, time=times, normalize=True)
 
 
 @pytest.mark.parametrize(