diff --git a/nixpkgs_review/builddir.py b/nixpkgs_review/builddir.py
index 56e26b13..a07576d8 100644
--- a/nixpkgs_review/builddir.py
+++ b/nixpkgs_review/builddir.py
@@ -39,6 +39,9 @@ def create_cache_directory(name: str) -> Union[Path, "TemporaryDirectory[str]"]:
 
         xdg_cache = Path(home).joinpath(".cache")
 
+    # There is no guarantee that environment variables are set to absolute paths.
+    xdg_cache = xdg_cache.absolute()
+
     counter = 0
     while True:
         try: