diff --git a/meter/fritzdect/fritzdect.go b/meter/fritzdect/fritzdect.go
index 8e148289b..ef28e850d 100644
--- a/meter/fritzdect/fritzdect.go
+++ b/meter/fritzdect/fritzdect.go
@@ -181,9 +181,8 @@ func createChallengeResponse(challenge, pass string) (string, error) {
 		return "", err
 	}
 
-	hash := md5.New()
-	hash.Write([]byte(utf16le))
+	hash := md5.Sum([]byte(utf16le))
+	md5hash := hex.EncodeToString(hash[:])
 
-	md5hash := hex.EncodeToString(hash.Sum(nil))
 	return challenge + "-" + md5hash, nil
 }
diff --git a/vehicle/aiways/identity.go b/vehicle/aiways/identity.go
index d09c900af..08ff78696 100644
--- a/vehicle/aiways/identity.go
+++ b/vehicle/aiways/identity.go
@@ -30,11 +30,9 @@ func NewIdentity(log *util.Logger) *Identity {
 }
 
 func (v *Identity) Login(user, password string) (int64, error) {
-	hash := md5.New()
-	hash.Write([]byte(password))
-
+	hash := md5.Sum([]byte(password))
+	v.hash = hex.EncodeToString(hash[:])
 	v.user = user
-	v.hash = hex.EncodeToString(hash.Sum(nil))
 
 	var res User
 
diff --git a/vehicle/niu.go b/vehicle/niu.go
index c3a6c618a..ebcca1235 100644
--- a/vehicle/niu.go
+++ b/vehicle/niu.go
@@ -69,9 +69,8 @@ func NewNiuFromConfig(other map[string]any) (api.Vehicle, error) {
 
 // login implements the Niu oauth2 api
 func (v *Niu) login() error {
-	hash := md5.New()
-	hash.Write([]byte(v.password))
-	md5hash := hex.EncodeToString(hash.Sum(nil))
+	hash := md5.Sum([]byte(v.password))
+	md5hash := hex.EncodeToString(hash[:])
 
 	data := url.Values{
 		"account":    {v.user},
diff --git a/vehicle/smart/hello/helper.go b/vehicle/smart/hello/helper.go
index 96dcd514a..d6717a183 100644
--- a/vehicle/smart/hello/helper.go
+++ b/vehicle/smart/hello/helper.go
@@ -25,9 +25,8 @@ func createSignature(method, path string, params url.Values, body io.Reader) (st
 			return "", "", "", err
 		}
 
-		hash := md5.New()
-		hash.Write(bytes)
-		md5Hash = base64.StdEncoding.EncodeToString(hash.Sum(nil))
+		hash := md5.Sum(bytes)
+		md5Hash = base64.StdEncoding.EncodeToString(hash[:])
 	}
 
 	payload := fmt.Sprintf(`application/json;responseformat=3