diff --git a/aiogram/utils/keyboard.py b/aiogram/utils/keyboard.py
index 2f529c60..3457ec13 100644
--- a/aiogram/utils/keyboard.py
+++ b/aiogram/utils/keyboard.py
@@ -141,7 +141,9 @@ class KeyboardBuilder(Generic[ButtonType], ABC):
         if not isinstance(size, int):
             raise ValueError("Only int sizes are allowed")
         if size not in range(self.min_width, self.max_width + 1):
-            raise ValueError(f"Row size {size} is not allowed, range: [{self.min_width}, {self.max_width}]")
+            raise ValueError(
+                f"Row size {size} is not allowed, range: [{self.min_width}, {self.max_width}]"
+            )
         return size
 
     def export(self) -> List[List[ButtonType]]: