diff --git a/client/src/AdriftClient.ts b/client/src/AdriftClient.ts
index 3e8ac70..e8fdec9 100644
--- a/client/src/AdriftClient.ts
+++ b/client/src/AdriftClient.ts
@@ -179,6 +179,8 @@ export class AdriftBareClient extends Client {
       }
     });
 
+    // coerce iframe Array type to our window array type
+    protocols = Array.from(protocols);
     let { send, close } = this.connection.wsconnect(
       remote,
       protocols,