diff --git a/pyproject.toml b/pyproject.toml
index 4e2e33c..3a5e742 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -68,3 +68,6 @@ extend-ignore = [
 line-length = 80
 indent-width = 4
 include = ["pyproject.toml", "typemap/**/*.py", "tests/**/*.py"]
+
+[tool.ruff.format]
+quote-style = "preserve"
diff --git a/tests/test_type_dir.py b/tests/test_type_dir.py
index c364513..c2b5e07 100644
--- a/tests/test_type_dir.py
+++ b/tests/test_type_dir.py
@@ -20,7 +20,7 @@
 
 from . import format_helper
 
-type OrGotcha[K] = K | Literal["gotcha!"]
+type OrGotcha[K] = K | Literal['gotcha!']
 
 type StrForInt[X] = (str | OrGotcha[X]) if X is int else (X | OrGotcha[X])
 
diff --git a/typemap/type_eval/_eval_typing.py b/typemap/type_eval/_eval_typing.py
index fa4d78e..0a2b0f7 100644
--- a/typemap/type_eval/_eval_typing.py
+++ b/typemap/type_eval/_eval_typing.py
@@ -55,7 +55,7 @@ class EvalContext:
 
 # `eval_types()` calls can be nested, context must be preserved
 _current_context: contextvars.ContextVar[EvalContext | None] = (
-    contextvars.ContextVar("_current_context", default=None)
+    contextvars.ContextVar('_current_context', default=None)
 )