diff --git a/test_regress/driver.py b/test_regress/driver.py
index 3db7d51c9..6f214145b 100755
--- a/test_regress/driver.py
+++ b/test_regress/driver.py
@@ -2635,8 +2635,7 @@ class VlTest:
                 self.error("Unknown trace file format " + traceFn)
 
     @staticmethod
-    def _vcd_parse_header(filename: str,
-                          root_scope: 'str | None' = None) -> 'tuple[dict, dict]':
+    def _vcd_parse_header(filename: str, root_scope: 'str | None' = None) -> 'tuple[dict, dict]':
         """Parse VCD header into hierarchy data and signal-code mapping.
 
         Returns (hier_data, var_codes) where:
diff --git a/test_regress/t/trace_split_struct_common.py b/test_regress/t/trace_split_struct_common.py
index 66017c950..8599faeea 100644
--- a/test_regress/t/trace_split_struct_common.py
+++ b/test_regress/t/trace_split_struct_common.py
@@ -8,7 +8,7 @@
 
 
 def run(test):
-    (fmt,) = test.parse_name(r"t_trace_split_struct_([a-z]+)")
+    (fmt, ) = test.parse_name(r"t_trace_split_struct_([a-z]+)")
 
     test.top_filename = "t/t_trace_split_struct.v"
     test.golden_filename = test.py_filename.rpartition(fmt)[0] + fmt + ".out"
diff --git a/test_regress/t/trace_struct_alias_common.py b/test_regress/t/trace_struct_alias_common.py
index be19cedc2..e5e418f68 100644
--- a/test_regress/t/trace_struct_alias_common.py
+++ b/test_regress/t/trace_struct_alias_common.py
@@ -8,7 +8,7 @@
 
 
 def run(test):
-    (fmt,) = test.parse_name(r"t_trace_struct_alias_([a-z]+)")
+    (fmt, ) = test.parse_name(r"t_trace_struct_alias_([a-z]+)")
 
     test.top_filename = "t/t_trace_struct_alias.v"
     test.golden_filename = test.py_filename.rpartition(fmt)[0] + fmt + ".out"