diff --git a/README.rst b/README.rst
index ec4f7b9..25a630c 100644
--- a/README.rst
+++ b/README.rst
@@ -66,6 +66,7 @@ of widgets:
  - `ReverseBar <http://progressbar-2.readthedocs.io/en/latest/_modules/progressbar/widgets.html#ReverseBar>`_
  - `RotatingMarker <http://progressbar-2.readthedocs.io/en/latest/_modules/progressbar/widgets.html#RotatingMarker>`_
  - `SimpleProgress <http://progressbar-2.readthedocs.io/en/latest/_modules/progressbar/widgets.html#SimpleProgress>`_
+ - `SmoothingETA <https://progressbar-2.readthedocs.io/en/latest/_modules/progressbar/widgets.html#SmoothingETA>`_
  - `Timer <http://progressbar-2.readthedocs.io/en/latest/_modules/progressbar/widgets.html#Timer>`_
 
 The progressbar module is very easy to use, yet very powerful. It will also
diff --git a/progressbar/widgets.py b/progressbar/widgets.py
index ffb201e..82b5b0c 100644
--- a/progressbar/widgets.py
+++ b/progressbar/widgets.py
@@ -665,7 +665,7 @@ def __init__(
     ):
         self.smoothing_parameters = smoothing_parameters or {}
         self.smoothing_algorithm = smoothing_algorithm(
-            **(self.smoothing_parameters or {}),
+            **self.smoothing_parameters,
         )
         ETA.__init__(self, **kwargs)
 
@@ -682,7 +682,7 @@ def __call__(
         if elapsed is None:  # pragma: no branch
             elapsed = data['time_elapsed']
 
-        self.smoothing_algorithm.update(value, elapsed)
+        value = self.smoothing_algorithm.update(value, elapsed)
         return ETA.__call__(self, progress, data, value=value, elapsed=elapsed)
 
 
diff --git a/tests/test_monitor_progress.py b/tests/test_monitor_progress.py
index 90e802a..6f0f148 100644
--- a/tests/test_monitor_progress.py
+++ b/tests/test_monitor_progress.py
@@ -85,10 +85,10 @@ def test_list_example(testdir) -> None:
     pprint.pprint(result.stderr.lines, width=70)
     result.stderr.fnmatch_lines([
         '  0% (0 of 9) |            | Elapsed Time: ?:00:00 ETA:  --:--:--',
-        ' 11% (1 of 9) |#           | Elapsed Time: ?:00:01 ETA:   ?:00:08',
-        ' 22% (2 of 9) |##          | Elapsed Time: ?:00:02 ETA:   ?:00:07',
-        ' 33% (3 of 9) |####        | Elapsed Time: ?:00:03 ETA:   ?:00:06',
-        ' 44% (4 of 9) |#####       | Elapsed Time: ?:00:04 ETA:   ?:00:05',
+        ' 11% (1 of 9) |#           | Elapsed Time: ?:00:01 ETA:   ?:00:16',
+        ' 22% (2 of 9) |##          | Elapsed Time: ?:00:02 ETA:   ?:00:11',
+        ' 33% (3 of 9) |####        | Elapsed Time: ?:00:03 ETA:   ?:00:08',
+        ' 44% (4 of 9) |#####       | Elapsed Time: ?:00:04 ETA:   ?:00:06',
         ' 55% (5 of 9) |######      | Elapsed Time: ?:00:05 ETA:   ?:00:04',
         ' 66% (6 of 9) |########    | Elapsed Time: ?:00:06 ETA:   ?:00:03',
         ' 77% (7 of 9) |#########   | Elapsed Time: ?:00:07 ETA:   ?:00:02',
@@ -144,14 +144,14 @@ def test_rapid_updates(testdir) -> None:
     result.stderr.fnmatch_lines(
         [
             '  0% (0 of 10) |      | Elapsed Time: 0:00:00 ETA:  --:--:--',
-            ' 10% (1 of 10) |      | Elapsed Time: 0:00:01 ETA:   0:00:09',
-            ' 20% (2 of 10) |#     | Elapsed Time: 0:00:02 ETA:   0:00:08',
-            ' 30% (3 of 10) |#     | Elapsed Time: 0:00:03 ETA:   0:00:07',
-            ' 40% (4 of 10) |##    | Elapsed Time: 0:00:04 ETA:   0:00:06',
-            ' 50% (5 of 10) |###   | Elapsed Time: 0:00:05 ETA:   0:00:05',
-            ' 60% (6 of 10) |###   | Elapsed Time: 0:00:07 ETA:   0:00:04',
-            ' 70% (7 of 10) |####  | Elapsed Time: 0:00:09 ETA:   0:00:03',
-            ' 80% (8 of 10) |####  | Elapsed Time: 0:00:11 ETA:   0:00:02',
+            ' 10% (1 of 10) |      | Elapsed Time: 0:00:01 ETA:   0:00:18',
+            ' 20% (2 of 10) |#     | Elapsed Time: 0:00:02 ETA:   0:00:12',
+            ' 30% (3 of 10) |#     | Elapsed Time: 0:00:03 ETA:   0:00:09',
+            ' 40% (4 of 10) |##    | Elapsed Time: 0:00:04 ETA:   0:00:07',
+            ' 50% (5 of 10) |###   | Elapsed Time: 0:00:05 ETA:   0:00:06',
+            ' 60% (6 of 10) |###   | Elapsed Time: 0:00:07 ETA:   0:00:05',
+            ' 70% (7 of 10) |####  | Elapsed Time: 0:00:09 ETA:   0:00:04',
+            ' 80% (8 of 10) |####  | Elapsed Time: 0:00:11 ETA:   0:00:03',
             ' 90% (9 of 10) |##### | Elapsed Time: 0:00:13 ETA:   0:00:01',
             '100% (10 of 10) |#####| Elapsed Time: 0:00:15 Time:  0:00:15',
         ],