diff --git a/src/pint/models/stand_alone_psr_binaries/BT_piecewise.py b/src/pint/models/stand_alone_psr_binaries/BT_piecewise.py
index 46247830a..4b1cefff5 100644
--- a/src/pint/models/stand_alone_psr_binaries/BT_piecewise.py
+++ b/src/pint/models/stand_alone_psr_binaries/BT_piecewise.py
@@ -165,7 +165,7 @@ def setup_internal_structures(self, valDict=None):
 
             # Uses the index for each toa array to create arrays where elements are the A1X/T0X to use with that toa
             if len(self.piecewise_parameter_information) > 0:
-                if hasattr(self,'_t'):
+                if hasattr(self, "_t"):
                     self.group_index_array = self.toa_belongs_in_group(self._t)
 
                     (