diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index a9361da2..36ebe68e 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -26,9 +26,10 @@ Fixed
 ^^^^^
 - Callable type with subclass return not showing the ``--*.help`` option (`#567
   <https://github.com/omni-us/jsonargparse/pull/567>`__).
-
 - Forward referenced types not compatible with `Type` typehint (`#576
-  <https://github.com/omni-us/jsonargparse/pull/576/>`__)
+  <https://github.com/omni-us/jsonargparse/pull/576/>`__).
+- Subclass nested in ``Iterable`` makes help fail (`#578
+  <https://github.com/omni-us/jsonargparse/pull/578>`__).
 
 Changed
 ^^^^^^^
diff --git a/jsonargparse/_typehints.py b/jsonargparse/_typehints.py
index b1a20bcf..50a119b8 100644
--- a/jsonargparse/_typehints.py
+++ b/jsonargparse/_typehints.py
@@ -1226,7 +1226,7 @@ def is_private(class_path):
         return "._" in class_path
 
     def add_subclasses(cl):
-        if hasattr(cl, "__args__") and get_typehint_origin(cl) in {List, list, Union}:
+        if hasattr(cl, "__args__") and get_typehint_origin(cl) in sequence_origin_types.union({Union}):
             for arg in cl.__args__:
                 add_subclasses(arg)
             return
diff --git a/jsonargparse_tests/test_subclasses.py b/jsonargparse_tests/test_subclasses.py
index 3d5d8149..a5a4d379 100644
--- a/jsonargparse_tests/test_subclasses.py
+++ b/jsonargparse_tests/test_subclasses.py
@@ -742,12 +742,14 @@ def __init__(self, p1: int = 0, p2: int = 0):
         pass
 
 
-def test_subclass_list_append_single(parser):
-    parser.add_argument("--val", type=Union[ListAppend, List[ListAppend]])
+@pytest.mark.parametrize("list_type", [List, Iterable])
+def test_subclass_list_append_single(parser, list_type):
+    parser.add_argument("--val", type=Union[ListAppend, list_type[ListAppend]])
     cfg = parser.parse_args([f"--val+={__name__}.ListAppend", "--val.p1=1", "--val.p2=2", "--val.p1=3"])
     assert cfg.val == [Namespace(class_path=f"{__name__}.ListAppend", init_args=Namespace(p1=3, p2=2))]
     cfg = parser.parse_args(["--val+=ListAppend", "--val.p2=2", "--val.p1=1"])
     assert cfg.val == [Namespace(class_path=f"{__name__}.ListAppend", init_args=Namespace(p1=1, p2=2))]
+    assert " --val+ " in get_parser_help(parser)
 
 
 @final