diff --git a/src/transports/PostMessageIframeTransport.ts b/src/transports/PostMessageIframeTransport.ts
index 8b3f91d..b051c1b 100644
--- a/src/transports/PostMessageIframeTransport.ts
+++ b/src/transports/PostMessageIframeTransport.ts
@@ -5,10 +5,12 @@ class PostMessageIframeTransport extends Transport {
   public uri: string;
   public frame: undefined | null | Window;
   public postMessageID: string;
+  public origin: string;
 
-  constructor(uri: string) {
+  constructor(uri: string, origin?: string) {
     super();
     this.uri = uri;
+    this.origin = origin || new URL(uri).origin;
     this.postMessageID = `post-message-transport-${Math.random()}`;
   }
   public createWindow(uri: string): Promise<Window | null> {
@@ -28,7 +30,8 @@ class PostMessageIframeTransport extends Transport {
     });
   }
   private messageHandler = (ev: MessageEvent) => {
-    this.transportRequestManager.resolveResponse(JSON.stringify(ev.data));
+    if (ev.origin === this.origin)
+      this.transportRequestManager.resolveResponse(JSON.stringify(ev.data));
   }
   public connect(): Promise<any> {
     const urlRegex = /^(http|https):\/\/.*$/;
@@ -46,7 +49,7 @@ class PostMessageIframeTransport extends Transport {
     const prom = this.transportRequestManager.addRequest(data, null);
     const notifications = getNotifications(data);
     if (this.frame) {
-      this.frame.postMessage((data as IJSONRPCData).request, "*");
+      this.frame.postMessage((data as IJSONRPCData).request, this.origin);
       this.transportRequestManager.settlePendingRequest(notifications);
     }
     return prom;
diff --git a/src/transports/PostMessageWindowTransport.ts b/src/transports/PostMessageWindowTransport.ts
index 1ad2fbb..2f53e40 100644
--- a/src/transports/PostMessageWindowTransport.ts
+++ b/src/transports/PostMessageWindowTransport.ts
@@ -18,10 +18,12 @@ class PostMessageTransport extends Transport {
   public uri: string;
   public frame: undefined | null | Window;
   public postMessageID: string;
+  public origin: string;
 
-  constructor(uri: string) {
+  constructor(uri: string, origin?: string) {
     super();
     this.uri = uri;
+    this.origin = origin || new URL(uri).origin;
     this.postMessageID = `post-message-transport-${Math.random()}`;
   }
 
@@ -36,7 +38,8 @@ class PostMessageTransport extends Transport {
   }
 
   private messageHandler = (ev: MessageEvent) => {
-    this.transportRequestManager.resolveResponse(JSON.stringify(ev.data));
+    if (ev.origin === this.origin)
+      this.transportRequestManager.resolveResponse(JSON.stringify(ev.data));
   }
 
   public connect(): Promise<any> {
@@ -55,7 +58,7 @@ class PostMessageTransport extends Transport {
     const prom = this.transportRequestManager.addRequest(data, null);
     const notifications = getNotifications(data);
     if (this.frame) {
-      this.frame.postMessage((data as IJSONRPCData).request, this.uri);
+      this.frame.postMessage((data as IJSONRPCData).request, this.origin);
       this.transportRequestManager.settlePendingRequest(notifications);
     }
     return prom;