diff --git a/otp.go b/otp.go
index 98ca8e9..9f20983 100644
--- a/otp.go
+++ b/otp.go
@@ -161,6 +161,9 @@ func (k *Key) URL() string {
 type Algorithm int
 
 const (
+	// AlgorithmSHA1 should be used for compatibility with Google Authenticator.
+	//
+	// See https://github.com/pquerna/otp/issues/55 for additional details.
 	AlgorithmSHA1 Algorithm = iota
 	AlgorithmSHA256
 	AlgorithmSHA512