diff --git a/src/main/java/org/gcube/oidc/rest/JWTToken.java b/src/main/java/org/gcube/oidc/rest/JWTToken.java
index 4e1fe84..9d6dde8 100644
--- a/src/main/java/org/gcube/oidc/rest/JWTToken.java
+++ b/src/main/java/org/gcube/oidc/rest/JWTToken.java
@@ -75,12 +75,12 @@ public class JWTToken implements Serializable {
         return payload;
     }
 
-    public String getExp() {
-        return (String) getPayload().get("exp");
+    public Long getExp() {
+        return (Long) getPayload().get("exp");
     }
 
     public Date getExpAsDate() {
-        return new Date(Long.getLong(getExp()) * 1000);
+        return new Date(getExp() * 1000);
     }
 
     public Calendar getExpAsCalendar() {