diff --git a/asv_bench/benchmarks/io/csv.py b/asv_bench/benchmarks/io/csv.py
index adb3dd95e3574..b8e8630e663ee 100644
--- a/asv_bench/benchmarks/io/csv.py
+++ b/asv_bench/benchmarks/io/csv.py
@@ -132,7 +132,7 @@ class ReadCSVConcatDatetimeBadDateValue(StringIORewind):
     param_names = ["bad_date_value"]
 
     def setup(self, bad_date_value):
-        self.StringIO_input = StringIO(("%s,\n" % bad_date_value) * 50000)
+        self.StringIO_input = StringIO((f"{bad_date_value},\n") * 50000)
 
     def time_read_csv(self, bad_date_value):
         read_csv(