diff --git a/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner.py b/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner.py
index eaf685aa1..7789f123d 100644
--- a/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner.py
+++ b/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner.py
@@ -64,7 +64,8 @@ def get_collate_fn(self):
     def train_step(self, batch, batch_ind):
         x, y = batch
         loss_dict = self.model(x, y)
-        return {'train_loss': loss_dict['total_loss']}
+        loss_dict['train_loss'] = sum(loss_dict.values())
+        return loss_dict
 
     def validate_step(self, batch, batch_ind):
         x, y = batch
@@ -83,10 +84,10 @@ def validate_end(self, outputs):
         num_class_ids = len(self.cfg.data.class_names)
         coco_eval = compute_coco_eval(outs, ys, num_class_ids)
 
-        metrics = {'map': 0.0, 'map50': 0.0}
+        metrics = {'mAP': 0.0, 'mAP50': 0.0}
         if coco_eval is not None:
             coco_metrics = coco_eval.stats
-            metrics = {'map': coco_metrics[0], 'map50': coco_metrics[1]}
+            metrics = {'mAP': coco_metrics[0], 'mAP50': coco_metrics[1]}
         return metrics
 
     def predict(self,
diff --git a/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner_config.py b/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner_config.py
index aeda0c07e..00dc73e63 100644
--- a/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner_config.py
+++ b/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_learner_config.py
@@ -6,6 +6,7 @@
 import albumentations as A
 
 from torchvision.models.detection.backbone_utils import resnet_fpn_backbone
+from torchvision.models.detection.faster_rcnn import FasterRCNN
 
 from rastervision.core.data import Scene
 from rastervision.pipeline.config import (Config, register_config, Field,
@@ -17,7 +18,6 @@
     ObjectDetectionImageDataset, ObjectDetectionSlidingWindowGeoDataset,
     ObjectDetectionRandomWindowGeoDataset)
 from rastervision.pytorch_learner.utils import adjust_conv_channels
-from torchvision.models.detection.faster_rcnn import FasterRCNN
 
 if TYPE_CHECKING:
     from rastervision.pytorch_learner.learner_config import SolverConfig
diff --git a/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_utils.py b/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_utils.py
index 5df52f8f3..3c1e17279 100644
--- a/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_utils.py
+++ b/rastervision_pytorch_learner/rastervision/pytorch_learner/object_detection_utils.py
@@ -317,7 +317,7 @@ def __init__(self,
     def forward(self,
                 input: torch.Tensor,
                 targets: Optional[Iterable[BoxList]] = None
-                ) -> Union[dict, List[BoxList]]:
+                ) -> Union[Dict[str, Any], List[BoxList]]:
         """Forward pass.
 
         Args:
@@ -340,10 +340,7 @@ def forward(self,
             # models: a dict with keys, 'boxes' and 'labels'.
             # Note: labels (class IDs) must start at 1.
             _targets = [self.boxlist_to_model_input_dict(bl) for bl in targets]
-
             loss_dict = self.model(input, _targets)
-            loss_dict['total_loss'] = sum(list(loss_dict.values()))
-
             return loss_dict
 
         outs = self.model(input)
@@ -353,8 +350,9 @@ def forward(self,
         return boxlists
 
     def boxlist_to_model_input_dict(self, boxlist: BoxList) -> dict:
-        """Convert BoxList to a dict compatible with torchvision detection
-        models. Also, make class labels 1-indexed.
+        """Convert BoxList to dict compatible w/ torchvision detection models.
+
+        Also, make class labels 1-indexed.
 
         Args:
             boxlist (BoxList): A BoxList with a "class_ids" field.
@@ -369,8 +367,9 @@ def boxlist_to_model_input_dict(self, boxlist: BoxList) -> dict:
         }
 
     def model_output_dict_to_boxlist(self, out: dict) -> BoxList:
-        """Convert torchvision detection dict to BoxList. Also, exclude any
-        null classes and make class labels 0-indexed.
+        """Convert model output dict to BoxList.
+
+        Also, exclude any null classes and make class labels 0-indexed.
 
         Args:
             out (dict): A dict output by a torchvision detection model in eval
diff --git a/rastervision_pytorch_learner/rastervision/pytorch_learner/regression_learner.py b/rastervision_pytorch_learner/rastervision/pytorch_learner/regression_learner.py
index 7a88dd7b8..09a6f7f7d 100644
--- a/rastervision_pytorch_learner/rastervision/pytorch_learner/regression_learner.py
+++ b/rastervision_pytorch_learner/rastervision/pytorch_learner/regression_learner.py
@@ -66,10 +66,9 @@ def validate_step(self, batch, batch_nb):
             torch.abs(out - y) / self.target_medians).sum(dim=0)
 
         metrics = {'val_loss': val_loss}
-        for ind, label in enumerate(self.cfg.data.class_names):
-            metrics['{}_abs_error'.format(label)] = abs_error[ind]
-            metrics['{}_scaled_abs_error'.format(label)] = scaled_abs_error[
-                ind]
+        for i, label in enumerate(self.cfg.data.class_names):
+            metrics[f'{label}_abs_error'] = abs_error[i]
+            metrics[f'{label}_scaled_abs_error'] = scaled_abs_error[i]
 
         return metrics
 
diff --git a/tests/pytorch_learner/test_object_detection_utils.py b/tests/pytorch_learner/test_object_detection_utils.py
index 5dc4216e6..69a103c9d 100644
--- a/tests/pytorch_learner/test_object_detection_utils.py
+++ b/tests/pytorch_learner/test_object_detection_utils.py
@@ -47,7 +47,6 @@ def test_train_output(self):
         self.assertRaises(Exception, lambda: model(x))
         out = model(x, y)
         self.assertIsInstance(out, dict)
-        self.assertIn('total_loss', out)
 
     def test_eval_output_with_bogus_class(self):
         true_num_classes = 3