diff --git a/guardian/src/main/java/com/auth0/android/guardian/sdk/Guardian.java b/guardian/src/main/java/com/auth0/android/guardian/sdk/Guardian.java
index d3eb8de..8a3d79c 100644
--- a/guardian/src/main/java/com/auth0/android/guardian/sdk/Guardian.java
+++ b/guardian/src/main/java/com/auth0/android/guardian/sdk/Guardian.java
@@ -260,7 +260,7 @@ public Builder enableLogging() {
          * @throws IllegalStateException when the builder was not configured correctly
          */
         public Guardian build() {
-            if (url == null) {
+            if (this.url == null) {
                 throw new IllegalStateException("You must set either a domain or an url");
             }
 
diff --git a/guardian/src/main/java/com/auth0/android/guardian/sdk/GuardianAPIClient.java b/guardian/src/main/java/com/auth0/android/guardian/sdk/GuardianAPIClient.java
index 8aa1a9a..f2d207b 100644
--- a/guardian/src/main/java/com/auth0/android/guardian/sdk/GuardianAPIClient.java
+++ b/guardian/src/main/java/com/auth0/android/guardian/sdk/GuardianAPIClient.java
@@ -358,7 +358,7 @@ public Builder enableLogging() {
          * @throws IllegalStateException when the builder was not configured correctly
          */
         public GuardianAPIClient build() {
-            if (url == null) {
+            if (this.url == null) {
                 throw new IllegalStateException("You must set either a domain or an url");
             }
 
@@ -398,7 +398,7 @@ public Response intercept(Chain chain) throws IOException {
 
             RequestFactory requestFactory = new RequestFactory(gson, client);
 
-            return new GuardianAPIClient(requestFactory, url);
+            return new GuardianAPIClient(requestFactory, this.url);
         }
     }
 }