diff --git a/build-aux/syntax-check.mk b/build-aux/syntax-check.mk
index 221c581a31bc005f20f3e8ed55a512849e2209c0..3bb9a90e9d473cb2ca5197a8d9fbc14520caaca6 100644
--- a/build-aux/syntax-check.mk
+++ b/build-aux/syntax-check.mk
@@ -888,7 +888,7 @@ FLAKE8_WHITESPACE = E211,E221,E222,E225,E226,E231,E261
 FLAKE8_BLANK_LINES = E301,E302,E303,E305
 FLAKE8_LINE_LENGTH = E501
 FLAKE8_STATEMENTS = E722,E741
-FLAKE8_WARNINGS = W504,W605
+FLAKE8_WARNINGS = W504
 
 FLAKE8_IGNORE = $(FLAKE8_INDENTATION),$\
 		$(FLAKE8_WHITESPACE),$\
diff --git a/docs/apibuild.py b/docs/apibuild.py
index 20ce926ae88b894ce1a889f2894b83c18deecb5c..7e4fbff07f0de0a17b14588dc44a657e486ba326 100755
--- a/docs/apibuild.py
+++ b/docs/apibuild.py
@@ -665,7 +665,7 @@ class CParser:
         for line in lines:
             line = line.lstrip().lstrip('*').lstrip()
 
-            m = re.match('([_.a-zA-Z0-9]+):(.*)', line)
+            m = re.match(r'([_.a-zA-Z0-9]+):(.*)', line)
             if m:
                 item = m.group(1)
                 line = m.group(2).lstrip()
@@ -1333,7 +1333,7 @@ class CParser:
                     while token[0] != "sep" or (token[1] != ',' and
                           token[1] != '}'):
                         # We might be dealing with '1U << 12' here
-                        value = value + re.sub("^(\d+)U$", "\\1", token[1])
+                        value = value + re.sub(r"^(\d+)U$", "\\1", token[1])
                         token = self.token()
                 else:
                     try:
@@ -2108,7 +2108,7 @@ class docBuilder:
                 if valhex != "":
                     output.write(" value_hex='%s'" % (valhex))
 
-                m = re.match("\(?1<<(\d+)\)?", info[0])
+                m = re.match(r"\(?1<<(\d+)\)?", info[0])
                 if m:
                     output.write(" value_bitshift='%s'" % (m.group(1)))