diff --git a/nibabel/openers.py b/nibabel/openers.py
index 9a306d4e4..35b10c20a 100644
--- a/nibabel/openers.py
+++ b/nibabel/openers.py
@@ -22,6 +22,7 @@
     from types import TracebackType
 
     from _typeshed import WriteableBuffer
+    from typing_extensions import Self
 
     ModeRT = ty.Literal['r', 'rt']
     ModeRB = ty.Literal['rb']
@@ -246,7 +247,7 @@ def close_if_mine(self) -> None:
         if self.me_opened:
             self.close()
 
-    def __enter__(self) -> Opener:
+    def __enter__(self) -> Self:
         return self
 
     def __exit__(
diff --git a/pyproject.toml b/pyproject.toml
index fa3f88116..0dd49c847 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -123,6 +123,7 @@ select = [
     "I",
     "PIE",
     "PLE",
+    "PYI",
     "Q",
     "RSE",
     "TCH",
@@ -143,6 +144,7 @@ ignore = [
     "C408",
     "C416",
     "PIE790",
+    "PYI024",
     # https://docs.astral.sh/ruff/formatter/#conflicting-lint-rules
     "W191",
     "E111",
diff --git a/tox.ini b/tox.ini
index 5df35c8d3..675526f94 100644
--- a/tox.ini
+++ b/tox.ini
@@ -181,6 +181,7 @@ deps =
   numpy
   pyzstd
   importlib_resources
+  typing_extensions
 skip_install = true
 commands =
   mypy nibabel