diff --git a/src/snek/static/event-handler.js b/src/snek/static/event-handler.js
index e3dbe76..7299982 100644
--- a/src/snek/static/event-handler.js
+++ b/src/snek/static/event-handler.js
@@ -3,8 +3,15 @@ export class EventHandler {
     this.subscribers = {};
   }
 
-  addEventListener(type, handler) {
+  addEventListener(type, handler, { once = false } = {}) {
     if (!this.subscribers[type]) this.subscribers[type] = [];
+    if (once) {
+      const originalHandler = handler;
+      handler = (...args) => {
+        originalHandler(...args);
+        this.removeEventListener(type, handler);
+      };
+    }
     this.subscribers[type].push(handler);
   }
 
@@ -12,4 +19,15 @@ export class EventHandler {
     if (this.subscribers[type])
       this.subscribers[type].forEach((handler) => handler(...data));
   }
+
+  removeEventListener(type, handler) {
+    if (!this.subscribers[type]) return;
+    this.subscribers[type] = this.subscribers[type].filter(
+      (h) => h !== handler
+    );
+
+    if (this.subscribers[type].length === 0) {
+      delete this.subscribers[type];
+    }
+  }
 }
diff --git a/src/snek/static/socket.js b/src/snek/static/socket.js
index 1131e8f..3c1dced 100644
--- a/src/snek/static/socket.js
+++ b/src/snek/static/socket.js
@@ -142,10 +142,9 @@ export class Socket extends EventHandler {
       method,
       args,
     };
-    const me = this;
     return new Promise((resolve) => {
-      me.addEventListener(call.callId, (data) => resolve(data));
-      me.sendJson(call);
+      this.addEventListener(call.callId, (data) => resolve(data), { once: true});
+      this.sendJson(call);
     });
   }
 }