diff --git a/tools/upend_js/api.ts b/tools/upend_js/api.ts
index 645a3fc..ab9d512 100644
--- a/tools/upend_js/api.ts
+++ b/tools/upend_js/api.ts
@@ -13,7 +13,7 @@ import type {
   StoreInfo,
   VaultInfo,
 } from "./types";
-import init_wasm from "upend_wasm";
+import init_wasm, { InitOutput } from "upend_wasm";
 import {
   AddressComponents,
   AddressTypeConstants,
@@ -27,8 +27,10 @@ export { AddressComponents };
 
 export class UpEndApi {
   private instanceUrl = "";
+
   private wasmPath: string | undefined;
   private wasmInitialized = false;
+  private wasmPromise: Promise<InitOutput> | undefined;
   private addressTypeConstants: AddressTypeConstants | undefined = undefined;
 
   private queryOnceLRU = new LRU<string, UpListing>({ max: 128 });
@@ -265,7 +267,15 @@ export class UpEndApi {
           "Path to WASM file not specified, cannot initialize WASM extensions."
         );
       }
-      await init_wasm(this.wasmPath);
+      if (this.wasmPromise) {
+        await this.wasmPromise;
+      } else {
+        dbg("Initializing WASM...");
+        this.wasmPromise = init_wasm(this.wasmPath);
+        await this.wasmPromise;
+        dbg("Wasm initialized.");
+      }
+
       this.wasmInitialized = true;
     }
   }