diff --git a/src/main/edu/wisc/doit/RpcNetidClient.php b/src/main/edu/wisc/doit/RpcNetidClient.php
index be4e7dbffc0c90563cfca280b8ad2ee974c132b6..7a6a9004cdcaeb1ca61cc58e9a89f463fc41dc69 100644
--- a/src/main/edu/wisc/doit/RpcNetidClient.php
+++ b/src/main/edu/wisc/doit/RpcNetidClient.php
@@ -47,11 +47,11 @@ interface RpcNetidClient {
 	 * Validates the answers to the NetID security questions for a given user
 	 * @param string $uid  the uid of the user to search for (typically the NetID)
 	 * @param RpcNetidStructQuestion[] $questions  array containing security questions for the user (Number and Answer required)
-	 * @param string $ip  ip address of the user (optional)
+	 * @param string $ip  ip address of the user
 	 * @return bool  true if the answers are correct, false otherwise
 	 * @throws edu\wisc\doit\RpcNetidClientSoapException if unexpected response from web service 
 	 */
-	function checkAnswers ( $uid, array $questions, $ip = "" );
+	function checkAnswers ( $uid, array $questions, $ip );
 	
 	/**
 	 * Retrieves the recovery email attached to the given user's uid
diff --git a/src/main/edu/wisc/doit/RpcNetidClientSoap.php b/src/main/edu/wisc/doit/RpcNetidClientSoap.php
index f46ee033f0babd20e8b5c80f0bf018af78d0f0b7..81a8c1a0f37849ab95ac38098fca554727f327f2 100644
--- a/src/main/edu/wisc/doit/RpcNetidClientSoap.php
+++ b/src/main/edu/wisc/doit/RpcNetidClientSoap.php
@@ -189,23 +189,21 @@ class RpcNetidClientSoap implements RpcNetidClient {
 	 * (non-PHPdoc)
 	 * @see \edu\wisc\doit\RpcNetidClient::checkAnswers()
 	 */
-	public function checkAnswers( $uid, array $questions, $ip = "" ){
+	public function checkAnswers( $uid, array $questions, $ip ){
 		
 		if( is_string($uid) !== true) {
 			throw new \InvalidArgumentException("uid parameter must be a string");
 		}
-		
-		if ( empty( $ip ) === false ) {
-			
-			if ( is_string( $ip ) !== true) {
-				throw new \InvalidArgumentException("ip parameter must be a string");
-			}
-			
-			if ( filter_var( $ip, FILTER_VALIDATE_IP ) === false ) {
-				throw new \DomainException( "Invalid IP address: $ip" );
-			}
+
 			
+		if ( is_string( $ip ) !== true) {
+			throw new \InvalidArgumentException("ip parameter must be a string");
+		}
+		
+		if ( filter_var( $ip, FILTER_VALIDATE_IP ) === false ) {
+			throw new \DomainException( "Invalid IP address: $ip" );
 		}
+
 		
 		// Create array of parameters for the SOAP client
 		$questionsParam = array( 'QuestionPair' => array() );