diff --git a/lib/hotp.php b/lib/hotp.php
index 7092fd9..3eff087 100644
--- a/lib/hotp.php
+++ b/lib/hotp.php
@@ -41,8 +41,8 @@ class HOTP extends OTP {
      *  seed the hmac hash function.
      *  @return integer the One Time Password
      */
-    public function at($count) {
-      return $this->generateOTP($count);
+    public function at($count,$g2f=false) {
+      return $this->generateOTP($count,$g2f);
     }
 
 
diff --git a/lib/otp.php b/lib/otp.php
index 77bcfe9..2a3acb2 100644
--- a/lib/otp.php
+++ b/lib/otp.php
@@ -78,7 +78,7 @@ public function __construct($secret, $opt = Array()) {
      * timestamp (see TOTP class).
      * @return integer the one-time password 
      */
-    public function generateOTP($input) {
+    public function generateOTP($input,$g2f = false) {
       $hash = hash_hmac($this->digest, $this->intToBytestring($input), $this->byteSecret());
       foreach(str_split($hash, 2) as $hex) { // stupid PHP has bin2hex but no hex2bin WTF
         $hmac[] = hexdec($hex);
@@ -88,8 +88,15 @@ public function generateOTP($input) {
         ($hmac[$offset + 1] & 0xFF) << 16 |
         ($hmac[$offset + 2] & 0xFF) << 8 |
         ($hmac[$offset + 3] & 0xFF);
+      if($g2f) return $this->normalizeOTP($code % pow(10, $this->digits));
       return $code % pow(10, $this->digits);
     }
+    /*
+    Add initial zeros for match with Google Authenticator App
+    */
+    public function normalizeOTP($otp){
+        return str_pad($otp,6,"0",STR_PAD_LEFT);
+    }
 
     /**
      * Returns the binary value of the base32 encoded secret
diff --git a/lib/totp.php b/lib/totp.php
index 10a1f42..845af8f 100644
--- a/lib/totp.php
+++ b/lib/totp.php
@@ -54,8 +54,8 @@ public function __construct($s, $opt = Array()) {
      *  used to seed the hmac hash function.
      *  @return integer the One Time Password
      */
-    public function at($timestamp) {
-      return $this->generateOTP($this->timecode($timestamp));
+    public function at($timestamp,$g2f = false) {
+      return $this->generateOTP($this->timecode($timestamp),$g2f);
     }
 
     /**
@@ -63,8 +63,8 @@ public function at($timestamp) {
      *
      *  @return integer the current One Time Password
      */
-    public function now() {
-      return $this->generateOTP($this->timecode(time()));
+    public function now($g2f = false) {
+      return $this->generateOTP($this->timecode(time()),$g2f);
     }
 
     /**