diff --git a/src/tyro/_calling.py b/src/tyro/_calling.py
index 8c9fe501..765d34ab 100644
--- a/src/tyro/_calling.py
+++ b/src/tyro/_calling.py
@@ -111,8 +111,11 @@ def get_value_from_arg(
                     # value, and the field default will be inspect.Parameter.empty.
                     if (
                         value in _fields.MISSING_AND_MISSING_NONPROP
-                        and field.is_positional_call()
-                        and arg.lowered.nargs in ("?", "*")
+                        and arg.field.is_positional()
+                        # nargs="?" is currently only used for optional positional
+                        # arguments when the underlying nargs for the primitive
+                        # constructor is 1. Logic for this is in _arguments.py.
+                        and arg.lowered.nargs == "*"
                     ):
                         value = []
                         should_cast = True
diff --git a/tests/test_custom_constructors.py b/tests/test_custom_constructors.py
index a4d8bdc5..ba5a55a5 100644
--- a/tests/test_custom_constructors.py
+++ b/tests/test_custom_constructors.py
@@ -1,10 +1,11 @@
 from __future__ import annotations
 
 import json
-from typing import Any, Dict, List, Union
+from typing import Any, Dict, List, Tuple, Union
 
 import numpy as np
 import pytest
+from helptext_utils import get_helptext_with_checks
 from typing_extensions import Annotated, Literal, get_args
 
 import tyro
@@ -136,3 +137,52 @@ def main(
     with pytest.raises(SystemExit):
         tyro.cli(main, args=["--field1"])
     assert tyro.cli(main, args=["--field1", "a", "b"]) == ["a", "b"]
+
+
+def test_min_length_custom_constructor_positional() -> None:
+    def main(
+        field1: tyro.conf.Positional[ListOfStringsWithMinimumLength], field2: int = 3
+    ) -> ListOfStringsWithMinimumLength:
+        del field2
+        return field1
+
+    with pytest.raises(SystemExit):
+        tyro.cli(main, args=[])
+    assert tyro.cli(main, args=["a", "b"]) == ["a", "b"]
+
+
+TupleCustomConstructor = Annotated[
+    Tuple[str, ...],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="A TUPLE METAVAR",
+        is_instance=lambda x: isinstance(x, tuple)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=lambda args: tuple(args),
+        str_from_instance=lambda args: list(args),
+    ),
+]
+
+
+def test_tuple_custom_constructors() -> None:
+    def main(field1: TupleCustomConstructor, field2: int = 3) -> tuple[str, ...]:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["--field1", "a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["--field1", "a"]) == ("a",)
+    assert tyro.cli(main, args=["--field1"]) == ()
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
+
+
+def test_tuple_custom_constructors_positional() -> None:
+    def main(
+        field1: tyro.conf.Positional[TupleCustomConstructor], field2: int = 3
+    ) -> tuple[str, ...]:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["a"]) == ("a",)
+    assert tyro.cli(main, args=[]) == ()
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
diff --git a/tests/test_positional_min_py38.py b/tests/test_positional_min_py38.py
index 15f8f791..5aae9de1 100644
--- a/tests/test_positional_min_py38.py
+++ b/tests/test_positional_min_py38.py
@@ -1,6 +1,11 @@
+from __future__ import annotations
+
+import sys
 from typing import List, Optional, Tuple
 
 import pytest
+from helptext_utils import get_helptext_with_checks
+from typing_extensions import Annotated
 
 import tyro
 
@@ -31,11 +36,12 @@ def main(
         assert tyro.cli(main, args="--x 1 --y 2 --z 3".split(" ")) == (1, 2, 3)
 
 
-def test_nested_positional():
-    class A:
-        def __init__(self, a: int, hello_world: int, /, c: int):
-            self.hello_world = hello_world
+class A:
+    def __init__(self, a: int, hello_world: int, /, c: int):
+        self.hello_world = hello_world
+
 
+def test_nested_positional():
     def nest1(a: int, b: int, thing: A, /, c: int) -> A:
         return thing
 
@@ -45,11 +51,12 @@ def nest1(a: int, b: int, thing: A, /, c: int) -> A:
         tyro.cli(nest1, args="0 1 2 3 4 4 --c 4".split(" "))
 
 
-def test_nested_positional_alt():
-    class B:
-        def __init__(self, a: int, b: int, /, c: int):
-            pass
+class B:
+    def __init__(self, a: int, b: int, /, c: int):
+        pass
 
+
+def test_nested_positional_alt():
     def nest2(a: int, b: int, /, thing: B, c: int):
         return thing
 
@@ -116,3 +123,101 @@ def main(x: Tuple[int, int], y: Tuple[str, str], /):
         return x, y
 
     assert tyro.cli(main, args="1 2 3 4".split(" ")) == ((1, 2), ("3", "4"))
+
+
+def make_list_of_strings_with_minimum_length(args: List[str]) -> List[str]:
+    if len(args) == 0:
+        raise ValueError("Expected at least one string")
+    return args
+
+
+ListOfStringsWithMinimumLength = Annotated[
+    List[str],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="STR [STR ...]",
+        is_instance=lambda x: isinstance(x, list)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=make_list_of_strings_with_minimum_length,
+        str_from_instance=lambda args: args,
+    ),
+]
+
+
+def test_min_length_custom_constructor_positional() -> None:
+    def main(
+        field1: ListOfStringsWithMinimumLength, /, field2: int = 3
+    ) -> ListOfStringsWithMinimumLength:
+        del field2
+        return field1
+
+    with pytest.raises(SystemExit):
+        tyro.cli(main, args=[])
+    assert tyro.cli(main, args=["a", "b"]) == ["a", "b"]
+
+
+TupleCustomConstructor = Annotated[
+    Tuple[str, ...],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="A TUPLE METAVAR",
+        is_instance=lambda x: isinstance(x, tuple)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=lambda args: tuple(args),
+        str_from_instance=lambda args: list(args),
+    ),
+]
+
+
+def test_tuple_custom_constructors_positional() -> None:
+    def main(field1: TupleCustomConstructor, /, field2: int = 3) -> Tuple[str, ...]:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["a"]) == ("a",)
+    assert tyro.cli(main, args=[]) == ()
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
+
+
+TupleCustomConstructor2 = Annotated[
+    Tuple[str, ...],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="A TUPLE METAVAR",
+        is_instance=lambda x: isinstance(x, tuple)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=lambda args: tuple(args),
+        str_from_instance=lambda args: list(args),
+    ),
+]
+
+
+if sys.version_info >= (3, 11):
+
+    def test_tuple_custom_constructors_positional_default_none() -> None:
+        # Waiting for typing_extensions with this fixed:
+        # https://github.com/python/typing_extensions/issues/310
+        def main(
+            field1: TupleCustomConstructor2 | None = None, /, field2: int = 3
+        ) -> Tuple[str, ...] | None:
+            del field2
+            return field1
+
+        assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+        assert tyro.cli(main, args=["a"]) == ("a",)
+        assert tyro.cli(main, args=[]) is None
+        assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
+
+
+def test_tuple_custom_constructors_positional_default_five() -> None:
+    def main(
+        field1: TupleCustomConstructor2 | int = 5, /, field2: int = 3
+    ) -> Tuple[str, ...] | int:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["a"]) == ("a",)
+    assert tyro.cli(main, args=[]) == 5
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
diff --git a/tests/test_py311_generated/test_custom_constructors_generated.py b/tests/test_py311_generated/test_custom_constructors_generated.py
index 85b25726..c92de8ae 100644
--- a/tests/test_py311_generated/test_custom_constructors_generated.py
+++ b/tests/test_py311_generated/test_custom_constructors_generated.py
@@ -1,10 +1,11 @@
 from __future__ import annotations
 
 import json
-from typing import Annotated, Any, Dict, List, Literal, get_args
+from typing import Annotated, Any, Dict, List, Literal, Tuple, get_args
 
 import numpy as np
 import pytest
+from helptext_utils import get_helptext_with_checks
 
 import tyro
 
@@ -135,3 +136,52 @@ def main(
     with pytest.raises(SystemExit):
         tyro.cli(main, args=["--field1"])
     assert tyro.cli(main, args=["--field1", "a", "b"]) == ["a", "b"]
+
+
+def test_min_length_custom_constructor_positional() -> None:
+    def main(
+        field1: tyro.conf.Positional[ListOfStringsWithMinimumLength], field2: int = 3
+    ) -> ListOfStringsWithMinimumLength:
+        del field2
+        return field1
+
+    with pytest.raises(SystemExit):
+        tyro.cli(main, args=[])
+    assert tyro.cli(main, args=["a", "b"]) == ["a", "b"]
+
+
+TupleCustomConstructor = Annotated[
+    Tuple[str, ...],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="A TUPLE METAVAR",
+        is_instance=lambda x: isinstance(x, tuple)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=lambda args: tuple(args),
+        str_from_instance=lambda args: list(args),
+    ),
+]
+
+
+def test_tuple_custom_constructors() -> None:
+    def main(field1: TupleCustomConstructor, field2: int = 3) -> tuple[str, ...]:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["--field1", "a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["--field1", "a"]) == ("a",)
+    assert tyro.cli(main, args=["--field1"]) == ()
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
+
+
+def test_tuple_custom_constructors_positional() -> None:
+    def main(
+        field1: tyro.conf.Positional[TupleCustomConstructor], field2: int = 3
+    ) -> tuple[str, ...]:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["a"]) == ("a",)
+    assert tyro.cli(main, args=[]) == ()
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
diff --git a/tests/test_py311_generated/test_positional_min_py38_generated.py b/tests/test_py311_generated/test_positional_min_py38_generated.py
index 15f8f791..cfcf35fe 100644
--- a/tests/test_py311_generated/test_positional_min_py38_generated.py
+++ b/tests/test_py311_generated/test_positional_min_py38_generated.py
@@ -1,6 +1,10 @@
-from typing import List, Optional, Tuple
+from __future__ import annotations
+
+import sys
+from typing import Annotated, List, Optional, Tuple
 
 import pytest
+from helptext_utils import get_helptext_with_checks
 
 import tyro
 
@@ -31,11 +35,12 @@ def main(
         assert tyro.cli(main, args="--x 1 --y 2 --z 3".split(" ")) == (1, 2, 3)
 
 
-def test_nested_positional():
-    class A:
-        def __init__(self, a: int, hello_world: int, /, c: int):
-            self.hello_world = hello_world
+class A:
+    def __init__(self, a: int, hello_world: int, /, c: int):
+        self.hello_world = hello_world
+
 
+def test_nested_positional():
     def nest1(a: int, b: int, thing: A, /, c: int) -> A:
         return thing
 
@@ -45,11 +50,12 @@ def nest1(a: int, b: int, thing: A, /, c: int) -> A:
         tyro.cli(nest1, args="0 1 2 3 4 4 --c 4".split(" "))
 
 
-def test_nested_positional_alt():
-    class B:
-        def __init__(self, a: int, b: int, /, c: int):
-            pass
+class B:
+    def __init__(self, a: int, b: int, /, c: int):
+        pass
 
+
+def test_nested_positional_alt():
     def nest2(a: int, b: int, /, thing: B, c: int):
         return thing
 
@@ -116,3 +122,101 @@ def main(x: Tuple[int, int], y: Tuple[str, str], /):
         return x, y
 
     assert tyro.cli(main, args="1 2 3 4".split(" ")) == ((1, 2), ("3", "4"))
+
+
+def make_list_of_strings_with_minimum_length(args: List[str]) -> List[str]:
+    if len(args) == 0:
+        raise ValueError("Expected at least one string")
+    return args
+
+
+ListOfStringsWithMinimumLength = Annotated[
+    List[str],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="STR [STR ...]",
+        is_instance=lambda x: isinstance(x, list)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=make_list_of_strings_with_minimum_length,
+        str_from_instance=lambda args: args,
+    ),
+]
+
+
+def test_min_length_custom_constructor_positional() -> None:
+    def main(
+        field1: ListOfStringsWithMinimumLength, /, field2: int = 3
+    ) -> ListOfStringsWithMinimumLength:
+        del field2
+        return field1
+
+    with pytest.raises(SystemExit):
+        tyro.cli(main, args=[])
+    assert tyro.cli(main, args=["a", "b"]) == ["a", "b"]
+
+
+TupleCustomConstructor = Annotated[
+    Tuple[str, ...],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="A TUPLE METAVAR",
+        is_instance=lambda x: isinstance(x, tuple)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=lambda args: tuple(args),
+        str_from_instance=lambda args: list(args),
+    ),
+]
+
+
+def test_tuple_custom_constructors_positional() -> None:
+    def main(field1: TupleCustomConstructor, /, field2: int = 3) -> Tuple[str, ...]:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["a"]) == ("a",)
+    assert tyro.cli(main, args=[]) == ()
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
+
+
+TupleCustomConstructor2 = Annotated[
+    Tuple[str, ...],
+    tyro.constructors.PrimitiveConstructorSpec(
+        nargs="*",
+        metavar="A TUPLE METAVAR",
+        is_instance=lambda x: isinstance(x, tuple)
+        and all(isinstance(i, str) for i in x),
+        instance_from_str=lambda args: tuple(args),
+        str_from_instance=lambda args: list(args),
+    ),
+]
+
+
+if sys.version_info >= (3, 11):
+
+    def test_tuple_custom_constructors_positional_default_none() -> None:
+        # Waiting for typing with this fixed:
+        # https://github.com/python/typing/issues/310
+        def main(
+            field1: TupleCustomConstructor2 | None = None, /, field2: int = 3
+        ) -> Tuple[str, ...] | None:
+            del field2
+            return field1
+
+        assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+        assert tyro.cli(main, args=["a"]) == ("a",)
+        assert tyro.cli(main, args=[]) is None
+        assert "A TUPLE METAVAR" in get_helptext_with_checks(main)
+
+
+def test_tuple_custom_constructors_positional_default_five() -> None:
+    def main(
+        field1: TupleCustomConstructor2 | int = 5, /, field2: int = 3
+    ) -> Tuple[str, ...] | int:
+        del field2
+        return field1
+
+    assert tyro.cli(main, args=["a", "b"]) == ("a", "b")
+    assert tyro.cli(main, args=["a"]) == ("a",)
+    assert tyro.cli(main, args=[]) == 5
+    assert "A TUPLE METAVAR" in get_helptext_with_checks(main)