Update bids/analysis/transformations/base.py
@@ -350,7 +350,7 @@ class Transformation(metaclass=ABCMeta):
if not all([compare_variables(fc, get_col_data(c))
for c in variables[1:]]):
if self._force_dense_align:
- msg += (" Forcing all sparse variables to dense in "
+ msg = ("Forcing all sparse variables to dense in "
"order to ensure proper alignment.")
sr = self.collection.sampling_rate
variables = [c.to_dense(sr) for c in variables]
