diff --git a/src/dolphin/masking.py b/src/dolphin/masking.py
index c5e9f7e8..2435ee69 100644
--- a/src/dolphin/masking.py
+++ b/src/dolphin/masking.py
@@ -109,10 +109,8 @@ def combine_mask_files(
         input_conventions = [MaskConvention.NUMPY] * len(mask_files)
     elif len(input_conventions) != len(mask_files):
         raise ValueError(
-            (
-                f"input_conventions ({len(input_conventions)}) must have the same"
-                f" length as mask_files ({len(mask_files)})"
-            ),
+            f"input_conventions ({len(input_conventions)}) must have the same"
+            f" length as mask_files ({len(mask_files)})",
         )
 
     # Uses the numpy convention (1 = invalid, 0 = valid) for combining logic