diff --git a/test/subset/subset_test_suite.py b/test/subset/subset_test_suite.py
index cb16e965c..f656f793d 100644
--- a/test/subset/subset_test_suite.py
+++ b/test/subset/subset_test_suite.py
@@ -33,7 +33,7 @@ class Test:
             return self.subset[0]
         elif self.subset == "no-unicodes":
             return ""
-        elif re.match("^U\+", self.subset):
+        elif re.match(r"^U\+", self.subset):
             s = re.sub(r"U\+", "", self.subset)
             return s
         else: