diff --git a/src/gitcloak/app.py b/src/gitcloak/app.py
index 26a0656..ae9e4b4 100644
--- a/src/gitcloak/app.py
+++ b/src/gitcloak/app.py
@@ -169,7 +169,7 @@ def preview_file(owner: str, repo: str, file_path: str):
         is_safe = False
 
         if content_type == "text/markdown":
-            base_url = f"/{owner}/{repo}/raw/main/{"/".join(file_path.split("/")[:-1])}".rstrip(
+            base_url = f"/{owner}/{repo}/raw/main/{'/'.join(file_path.split('/')[:-1])}".rstrip(
                 "/"
             )
             file_content = RelativeURLRewriter(base_url).convert(