diff --git a/tomlkit/items.py b/tomlkit/items.py
index f2741dc1..61806739 100644
--- a/tomlkit/items.py
+++ b/tomlkit/items.py
@@ -291,7 +291,7 @@ def __init__(self, _, trivia, raw):  # type: (int, Trivia, str) -> None
         self._raw = raw
         self._sign = False
 
-        if re.match("^[+\-]\d+$", raw):
+        if re.match(r"^[+\-]\d+$", raw):
             self._sign = True
 
     @property
@@ -358,7 +358,7 @@ def __init__(self, _, trivia, raw):  # type: (float, Trivia, str) -> None
         self._raw = raw
         self._sign = False
 
-        if re.match("^[+\-].+$", raw):
+        if re.match(r"^[+\-].+$", raw):
             self._sign = True
 
     @property