diff --git a/moto/s3/responses.py b/moto/s3/responses.py
index 56f380872..0d1316811 100644
--- a/moto/s3/responses.py
+++ b/moto/s3/responses.py
@@ -1394,7 +1394,7 @@ class S3Response(BaseResponse):
         checksum_value = request.headers.get(checksum_header)
         if not checksum_value and checksum_algorithm:
             # Extract the checksum-value from the body first
-            search = re.search(b"x-amz-checksum-\w+:(\w+={1,2})", body)
+            search = re.search(rb"x-amz-checksum-\w+:(\w+={1,2})", body)
             checksum_value = search.group(1) if search else None
 
         if checksum_value:
diff --git a/setup.cfg b/setup.cfg
index 41dc011c6..3f61eaae5 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -15,4 +15,4 @@ ignore-paths=moto/packages
 [pylint.'MESSAGES CONTROL']
 disable = W,C,R,E
 # future sensible checks = super-init-not-called, unspecified-encoding, undefined-loop-variable
-enable = arguments-renamed, dangerous-default-value, deprecated-module, function-redefined, import-self, redefined-builtin, redefined-outer-name, reimported, pointless-statement, super-with-arguments, unused-argument, unused-import, unused-variable, useless-else-on-loop, wildcard-import
+enable = anomalous-backslash-in-string, arguments-renamed, dangerous-default-value, deprecated-module, function-redefined, import-self, redefined-builtin, redefined-outer-name, reimported, pointless-statement, super-with-arguments, unused-argument, unused-import, unused-variable, useless-else-on-loop, wildcard-import