diff --git a/setup.py b/setup.py
index 82055176e..4265667fb 100644
--- a/setup.py
+++ b/setup.py
@@ -19,7 +19,7 @@ def replace(name: str, regex: Pattern[str], replacement: str, content: str) -> s
     if modified_content != content:
         return modified_content
     raise RuntimeError(
-        f"The {name} wasn't found in README.rst using the pattern '{regex.pattern}'"
+        f"The {name} wasn't found in README.rst using the pattern {regex.pattern!r}"
     )
 
 
diff --git a/src/darker/__main__.py b/src/darker/__main__.py
index 190c27d25..206f0e681 100644
--- a/src/darker/__main__.py
+++ b/src/darker/__main__.py
@@ -413,7 +413,7 @@ def main(  # pylint: disable=too-many-locals,too-many-branches,too-many-statemen
         elif revrange.rev2 != WORKTREE:
             raise ArgumentError(
                 Action(["-r", "--revision"], "revision"),
-                f"Can't write reformatted files for revision '{revrange.rev2}'."
+                f"Can't write reformatted files for revision {revrange.rev2!r}."
                 " Either --diff or --check must be used.",
             )
 
diff --git a/src/darker/tests/test_main.py b/src/darker/tests/test_main.py
index 01a341712..cd7e7abd8 100644
--- a/src/darker/tests/test_main.py
+++ b/src/darker/tests/test_main.py
@@ -673,7 +673,7 @@ def test_main_historical_pre_commit(git_repo, monkeypatch):
         ArgumentError,
         match=(
             re.escape(
-                f"Can't write reformatted files for revision '{older_commit}'."
+                f"Can't write reformatted files for revision {older_commit!r}."
                 " Either --diff or --check must be used."
             )
         ),