diff --git a/gradle.properties b/gradle.properties
index ec1943f..a3315df 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1 +1 @@
-version=2.7.0
\ No newline at end of file
+version=2.8.0
\ No newline at end of file
diff --git a/src/main/java/com/authsignal/model/ChallengeResponse.java b/src/main/java/com/authsignal/model/ChallengeResponse.java
index 1cb4acc..10f8bf9 100644
--- a/src/main/java/com/authsignal/model/ChallengeResponse.java
+++ b/src/main/java/com/authsignal/model/ChallengeResponse.java
@@ -2,4 +2,5 @@
 
 public class ChallengeResponse extends ApiModel {
     public String challengeId;
+    public Long expiresAt;
 }
\ No newline at end of file
diff --git a/src/main/java/com/authsignal/model/GetChallengeResponse.java b/src/main/java/com/authsignal/model/GetChallengeResponse.java
index b6f284f..f825451 100644
--- a/src/main/java/com/authsignal/model/GetChallengeResponse.java
+++ b/src/main/java/com/authsignal/model/GetChallengeResponse.java
@@ -2,7 +2,7 @@
 
 public class GetChallengeResponse extends ApiModel {
     public String challengeId;
-    public Integer expiresAt;
+    public Long expiresAt;
     public VerificationMethodType verificationMethod;
     public SmsChannel smsChannel;
     public String phoneNumber;