diff --git a/siwe.go b/siwe.go
index e9b9e5b..7be0341 100644
--- a/siwe.go
+++ b/siwe.go
@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -79,13 +80,13 @@ func InitMessage(domain, address, uri, nonce string, options map[string]interfac
 
 	var chainId int
 	if val, ok := options["chainId"]; ok {
-		switch val.(type) {
+		switch tv := val.(type) {
 		case float64:
-			chainId = int(val.(float64))
+			chainId = int(tv)
 		case int:
-			chainId = val.(int)
+			chainId = tv
 		case string:
-			parsed, err := strconv.Atoi(val.(string))
+			parsed, err := strconv.Atoi(tv)
 			if err != nil {
 				return nil, &InvalidMessage{"Invalid format for field `chainId`, must be an integer"}
 			}
@@ -136,10 +137,8 @@ func InitMessage(domain, address, uri, nonce string, options map[string]interfac
 
 	var resources []url.URL
 	if val, ok := options["resources"]; ok {
-		switch val.(type) {
-		case []url.URL:
-			resources = val.([]url.URL)
-		default:
+		resources, ok = val.([]url.URL)
+		if !ok {
 			return nil, &InvalidMessage{"`resources` must be a []url.URL"}
 		}
 	}
@@ -165,7 +164,6 @@ func InitMessage(domain, address, uri, nonce string, options map[string]interfac
 
 func parseMessage(message string) (map[string]interface{}, error) {
 	match := _SIWE_MESSAGE.FindStringSubmatch(message)
-
 	if match == nil {
 		return nil, &InvalidMessage{"Message could not be parsed"}
 	}
@@ -177,18 +175,18 @@ func parseMessage(message string) (map[string]interface{}, error) {
 		}
 	}
 
-	if _, ok := result["domain"]; !ok {
+	domain, ok := result["domain"].(string)
+	if !ok {
 		return nil, &InvalidMessage{"`domain` must not be empty"}
 	}
-	domain := result["domain"].(string)
 	if ok, err := validateDomain(&domain); !ok {
 		return nil, err
 	}
 
-	if _, ok := result["uri"]; !ok {
+	uri, ok := result["uri"].(string)
+	if !ok {
 		return nil, &InvalidMessage{"`domain` must not be empty"}
 	}
-	uri := result["uri"].(string)
 	if _, err := validateURI(&uri); err != nil {
 		return nil, err
 	}
@@ -200,12 +198,20 @@ func parseMessage(message string) (map[string]interface{}, error) {
 	}
 
 	if val, ok := result["resources"]; ok {
-		resources := strings.Split(val.(string), "\n- ")[1:]
+		resourcesStr, ok := val.(string)
+		if !ok {
+			return nil, &InvalidMessage{fmt.Sprintf("resources is not a string but %T", val)}
+		}
+		resources := strings.Split(resourcesStr, "\n- ")
+		if len(resources) < 1 {
+			return nil, &InvalidMessage{"expected at least one resource"}
+		}
+		resources = resources[1:]
 		validateResources := make([]url.URL, len(resources))
 		for i, resource := range resources {
 			validateResource, err := url.Parse(resource)
 			if err != nil {
-				return nil, &InvalidMessage{fmt.Sprintf("Invalid format for field `resources` at position %d", i)}
+				return nil, &InvalidMessage{fmt.Sprintf("Invalid format for field `resources` at position %d: %s", i, err)}
 			}
 			validateResources[i] = *validateResource
 		}
@@ -237,11 +243,9 @@ func ParseMessage(message string) (*Message, error) {
 	return parsed, nil
 }
 
-func (m *Message) eip191Hash() common.Hash {
-	// Ref: https://stackoverflow.com/questions/49085737/geth-ecrecover-invalid-signature-recovery-id
+func (m *Message) eip191Hash() []byte {
 	data := []byte(m.String())
-	msg := fmt.Sprintf("\x19Ethereum Signed Message:\n%d%s", len(data), data)
-	return crypto.Keccak256Hash([]byte(msg))
+	return accounts.TextHash(data)
 }
 
 // ValidNow validates the time constraints of the message at current time.
@@ -283,7 +287,7 @@ func (m *Message) VerifyEIP191(signature string) (*ecdsa.PublicKey, error) {
 		return nil, &InvalidSignature{"Invalid signature recovery byte"}
 	}
 
-	pkey, err := crypto.SigToPub(m.eip191Hash().Bytes(), sigBytes)
+	pkey, err := crypto.SigToPub(m.eip191Hash(), sigBytes)
 	if err != nil {
 		return nil, &InvalidSignature{"Failed to recover public key from signature"}
 	}
diff --git a/siwe_test.go b/siwe_test.go
index 5c4bb5e..a47c349 100644
--- a/siwe_test.go
+++ b/siwe_test.go
@@ -3,7 +3,7 @@ package siwe
 import (
 	"crypto/ecdsa"
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"net/url"
 	"os"
 	"strconv"
@@ -239,7 +239,7 @@ func TestValidate(t *testing.T) {
 	assert.Nil(t, err)
 
 	hash := message.eip191Hash()
-	signature, err := crypto.Sign(hash.Bytes(), privateKey)
+	signature, err := crypto.Sign(hash, privateKey)
 	signature[64] += 27
 
 	assert.Nil(t, err)
@@ -257,7 +257,7 @@ func TestValidateTampered(t *testing.T) {
 	assert.Nil(t, err)
 
 	hash := message.eip191Hash()
-	signature, err := crypto.Sign(hash.Bytes(), privateKey)
+	signature, err := crypto.Sign(hash, privateKey)
 	signature[64] += 27
 
 	assert.Nil(t, err)
@@ -408,11 +408,12 @@ func TestGlobalTestVector(t *testing.T) {
 	}
 
 	for test, file := range files {
-		data, _ := ioutil.ReadAll(file)
+		data, err := io.ReadAll(file)
+		assert.NoError(t, err, test)
 
 		var result map[string]interface{}
-		err := json.Unmarshal([]byte(data), &result)
-		assert.Nil(t, err)
+		err = json.Unmarshal([]byte(data), &result)
+		assert.NoError(t, err)
 
 		switch test {
 		case "parsing-negative":