diff --git a/validation.go b/validation.go
index 56ffa13..31188bb 100644
--- a/validation.go
+++ b/validation.go
@@ -10,13 +10,18 @@ import (
 	"sort"
 )
 
+// ValidateIncomingRequest returns an error if the incoming req could not be
+// validated as coming from Twilio.
+//
+// This process is frequently error prone, especially if you are running behind
+// a proxy, or Twilio is making requests with a port in the URL.
 // See https://www.twilio.com/docs/security#validating-requests for more information
-func (c *Client) ValidateIncomingRequest(host string, req *http.Request) (err error) {
+func ValidateIncomingRequest(host string, authToken string, req *http.Request) (err error) {
 	err = req.ParseForm()
 	if err != nil {
 		return
 	}
-	err = c.validateIncomingRequest(host, req.URL.String(), req.Form, req.Header.Get("X-Twilio-Signature"))
+	err = validateIncomingRequest(host, authToken, req.URL.String(), req.Form, req.Header.Get("X-Twilio-Signature"))
 	if err != nil {
 		return
 	}
@@ -24,8 +29,8 @@ func (c *Client) ValidateIncomingRequest(host string, req *http.Request) (err er
 	return
 }
 
-func (c *Client) validateIncomingRequest(host string, URL string, postForm url.Values, xTwilioSignature string) (err error) {
-	expectedTwilioSignature := c.GetExpectedTwilioSignature(host, URL, postForm)
+func validateIncomingRequest(host string, authToken string, URL string, postForm url.Values, xTwilioSignature string) (err error) {
+	expectedTwilioSignature := GetExpectedTwilioSignature(host, authToken, URL, postForm)
 	if xTwilioSignature != expectedTwilioSignature {
 		err = errors.New("Bad X-Twilio-Signature")
 		return
@@ -34,7 +39,7 @@ func (c *Client) validateIncomingRequest(host string, URL string, postForm url.V
 	return
 }
 
-func (c *Client) GetExpectedTwilioSignature(host string, URL string, postForm url.Values) (expectedTwilioSignature string) {
+func GetExpectedTwilioSignature(host string, authToken string, URL string, postForm url.Values) (expectedTwilioSignature string) {
 	// Take the full URL of the request URL you specify for your
 	// phone number or app, from the protocol (https...) through
 	// the end of the query string (everything after the ?).
@@ -57,7 +62,7 @@ func (c *Client) GetExpectedTwilioSignature(host string, URL string, postForm ur
 
 	// Sign the resulting string with HMAC-SHA1 using your AuthToken
 	// as the key (remember, your AuthToken's case matters!).
-	mac := hmac.New(sha1.New, []byte(c.AuthToken))
+	mac := hmac.New(sha1.New, []byte(authToken))
 	mac.Write([]byte(str))
 	expectedMac := mac.Sum(nil)
 
diff --git a/validation_test.go b/validation_test.go
index 9022698..1c03cf9 100644
--- a/validation_test.go
+++ b/validation_test.go
@@ -9,7 +9,6 @@ import (
 func TestClientValidateIncomingRequest(t *testing.T) {
 	// Based on example at https://www.twilio.com/docs/security#validating-requests
 	authToken := "12345"
-	twilioClient := NewClient("", authToken, nil)
 	host := "https://mycompany.com"
 	URL := "/myapp.php?foo=1&bar=2"
 	xTwilioSignature := "RSOYDt4T1cUTdK1PDd93/VVr8B8="
@@ -21,14 +20,14 @@ func TestClientValidateIncomingRequest(t *testing.T) {
 		"CallSid": {"CA1234567890ABCDE"},
 	}
 
-	err := twilioClient.validateIncomingRequest(host, URL, postForm, xTwilioSignature)
+	err := validateIncomingRequest(host, authToken, URL, postForm, xTwilioSignature)
 	if err != nil {
 		fmt.Println("Unexpected error:", err)
 		t.Fail()
 	}
 
 	URL += "&cat=3"
-	err = twilioClient.validateIncomingRequest(host, URL, postForm, xTwilioSignature)
+	err = validateIncomingRequest(host, authToken, URL, postForm, xTwilioSignature)
 	if err == nil {
 		fmt.Println("Expected an error but got none")
 		t.Fail()