diff --git a/poethepoet/task/sequence.py b/poethepoet/task/sequence.py
index dd3b0d879..e15fac57a 100644
--- a/poethepoet/task/sequence.py
+++ b/poethepoet/task/sequence.py
@@ -75,7 +75,10 @@ def __init__(
 
                 subtask_name = (
                     sub_task_def
-                    if isinstance(sub_task_def, str)
+                    if (
+                        isinstance(sub_task_def, str)
+                        and (sub_task_def[0].isalpha() or sub_task_def[0] == "_")
+                    )
                     else SequenceTask._subtask_name(name, index)
                 )
                 task_type_key = self.task_type.resolve_task_type(
diff --git a/tests/fixtures/sequences_project/pyproject.toml b/tests/fixtures/sequences_project/pyproject.toml
index f0c8b66c5..602b4870f 100644
--- a/tests/fixtures/sequences_project/pyproject.toml
+++ b/tests/fixtures/sequences_project/pyproject.toml
@@ -61,3 +61,7 @@ sequence = [
   {script = "os:getcwd()", cwd = ".", print_result = true}
 ]
 cwd = "my_package"
+
+[tool.poe.tasks.setup]
+default_item_type = "cmd"
+sequence = ["./tools/poetry-ci-install.sh"]