diff --git a/spinn_front_end_common/interface/interface_functions/graph_data_specification_writer.py b/spinn_front_end_common/interface/interface_functions/graph_data_specification_writer.py
index 18b03752c..d72706785 100644
--- a/spinn_front_end_common/interface/interface_functions/graph_data_specification_writer.py
+++ b/spinn_front_end_common/interface/interface_functions/graph_data_specification_writer.py
@@ -62,8 +62,8 @@ class _GraphDataSpecificationWriter(object):
 
     def __init__(self) -> None:
         self._sdram_usage: Dict[Tuple[int, int], int] = defaultdict(lambda: 0)
-        self._vertices_by_chip: Dict[Tuple[int, int],
-                                List[AbstractGeneratesDataSpecification]] =\
+        self._vertices_by_chip: \
+            Dict[Tuple[int, int], List[AbstractGeneratesDataSpecification]] =\
             defaultdict(list)
 
     def run(self,