diff --git a/src/datasets/features/features.py b/src/datasets/features/features.py
index 50df83bfb06..aa58e8ce57a 100644
--- a/src/datasets/features/features.py
+++ b/src/datasets/features/features.py
@@ -832,7 +832,7 @@ def int2str(self, values: Union[int, Iterable]):
         """Conversion integer => class name string."""
         if not isinstance(values, int) and not isinstance(values, Iterable):
             raise ValueError(
-                "Values {values} should be an integer or an Iterable (list, numpy array, pytorch, tensorflow tensors)"
+                f"Values {values} should be an integer or an Iterable (list, numpy array, pytorch, tensorflow tensors)"
             )
         return_list = True
         if isinstance(values, int):