diff --git a/tests/extmod/re_namedclass.py b/tests/extmod/re_namedclass.py
index 442172f4ab..e712566719 100644
--- a/tests/extmod/re_namedclass.py
+++ b/tests/extmod/re_namedclass.py
@@ -31,6 +31,6 @@ m = re.match(r"(([0-9]*)([a-z]*)\d*)", "1234hello567")
 print_groups(m)
 
 # named class within a class set
-print_groups(re.match("([^\s]+)\s*([^\s]+)", "1 23"))
-print_groups(re.match("([\s\d]+)([\W]+)", "1  2-+="))
-print_groups(re.match("([\W]+)([^\W]+)([^\S]+)([^\D]+)", " a_1 23"))
+print_groups(re.match(r"([^\s]+)\s*([^\s]+)", "1 23"))
+print_groups(re.match(r"([\s\d]+)([\W]+)", "1  2-+="))
+print_groups(re.match(r"([\W]+)([^\W]+)([^\S]+)([^\D]+)", " a_1 23"))
diff --git a/tests/extmod/re_sub.py b/tests/extmod/re_sub.py
index 229c0e63ee..2c7c6c10f1 100644
--- a/tests/extmod/re_sub.py
+++ b/tests/extmod/re_sub.py
@@ -15,9 +15,9 @@ def multiply(m):
     return str(int(m.group(0)) * 2)
 
 
-print(re.sub("\d+", multiply, "10 20 30 40 50"))
+print(re.sub(r"\d+", multiply, "10 20 30 40 50"))
 
-print(re.sub("\d+", lambda m: str(int(m.group(0)) // 2), "10 20 30 40 50"))
+print(re.sub(r"\d+", lambda m: str(int(m.group(0)) // 2), "10 20 30 40 50"))
 
 
 def A():