diff --git a/tests/zarrtiff/tiff_fsspec.py b/tests/zarrtiff/tiff_fsspec.py
index f8f0ca834..eb9b1665f 100644
--- a/tests/zarrtiff/tiff_fsspec.py
+++ b/tests/zarrtiff/tiff_fsspec.py
@@ -20,6 +20,7 @@
 
 
 def _parse_svs_metadata(pages: TiffPages) -> dict[str, Any]:
+    # Copy/paste from TIFFWSIReader._parse_svs_metadata, extract to the util method.
     """Extract SVS-specific metadata."""
     raw = {}
     mpp: list[float] | None = None
@@ -40,8 +41,10 @@ def parse_svs_tag(string: str) -> tuple[str, Number | str | datetime]:
         """Parse SVS key-value string."""
         pair = string.split("=")
         if len(pair) != EXPECTED_KEY_VALUE_PAIRS:
-            msg = "Invalid metadata. Expected string of the format 'key=value'."
-            raise ValueError(msg)
+            invalid_metadata_msg = (
+                "Invalid metadata. Expected string of the format 'key=value'."
+            )
+            raise ValueError(invalid_metadata_msg)
 
         key, value_string = pair
         key = key.strip()