diff --git a/content/guides/end-call.md b/content/guides/end-call.md
index 243561c..07a0874 100644
--- a/content/guides/end-call.md
+++ b/content/guides/end-call.md
@@ -32,7 +32,7 @@ function endCall() {
   switch(session.state) {
     case SessionState.Initial:
     case SessionState.Establishing:
-      if (session instanceOf Inviter) {
+      if (session instanceof Inviter) {
         // An unestablished outgoing session
         session.cancel();
       } else {