diff --git a/src/_griffe/git.py b/src/_griffe/git.py
index 4b5b45fc..cc2817c8 100644
--- a/src/_griffe/git.py
+++ b/src/_griffe/git.py
@@ -5,8 +5,10 @@
 from __future__ import annotations
 
 import os
+import re
 import shutil
 import subprocess
+import unicodedata
 from contextlib import contextmanager
 from pathlib import Path
 from tempfile import TemporaryDirectory
@@ -17,6 +19,12 @@
 _WORKTREE_PREFIX = "griffe-worktree-"
 
 
+def _normalize(value: str) -> str:
+    value = unicodedata.normalize("NFKC", value)
+    value = re.sub(r"[^\w]+", "-", value)
+    return re.sub(r"[-\s]+", "-", value).strip("-")
+
+
 def assert_git_repo(path: str | Path) -> None:
     """Assert that a directory is a Git repository.
 
@@ -105,7 +113,7 @@ def tmp_worktree(repo: str | Path = ".", ref: str = "HEAD") -> Iterator[Path]:
     assert_git_repo(repo)
     repo_name = Path(repo).resolve().name
     with TemporaryDirectory(prefix=f"{_WORKTREE_PREFIX}{repo_name}-{ref}-") as tmp_dir:
-        branch = f"griffe_{ref}"
+        branch = _normalize(ref)
         location = os.path.join(tmp_dir, branch)  # noqa: PTH118
         process = subprocess.run(
             ["git", "-C", repo, "worktree", "add", "-b", branch, location, ref],