diff --git a/app/static/js/services/soundfontPlayer.js b/app/static/js/services/soundfontPlayer.js
index c1339cf..847ea19 100644
--- a/app/static/js/services/soundfontPlayer.js
+++ b/app/static/js/services/soundfontPlayer.js
@@ -68,7 +68,8 @@
             } catch (e) {
                 console.warn("[SonicSF] SpessaSynth AudioWorklet init failed:", e, "- trying WorkerSynthesizer...");
                 try {
-                    const { WorkerSynthesizer } = await import(window.__SpessaSynthCDN + "index.js");
+                    const mod = await import("https://esm.sh/spessasynth_lib@4.3.1");
+                    const WorkerSynthesizer = mod.WorkerSynthesizer;
                     _synthInstance = new WorkerSynthesizer(audioContext);
                     await _synthInstance.isReady;
                     _initialized = true;
diff --git a/app/templates/index.html b/app/templates/index.html
index f5ce43e..af5ed9f 100644
--- a/app/templates/index.html
+++ b/app/templates/index.html
@@ -11,10 +11,10 @@
     <script src="https://unpkg.com/react@18.3.1/umd/react.production.min.js"></script>
     <script src="https://unpkg.com/react-dom@18.3.1/umd/react-dom.production.min.js"></script>
     <script type="module">
-      import { WorkletSynthesizer } from 'https://cdn.jsdelivr.net/npm/spessasynth_lib@4.3.1/dist/index.js';
+      import { WorkletSynthesizer } from 'https://esm.sh/spessasynth_lib@4.3.1';
       window.SpessaSynthClass = WorkletSynthesizer;
       window.__SpessaSynthCDN = 'https://cdn.jsdelivr.net/npm/spessasynth_lib@4.3.1/dist/';
-      console.log('[SonicSF] SpessaSynth library loaded.');
+      console.log('[SonicSF] SpessaSynth library loaded via esm.sh.');
     </script>
     <script src="/static/js/services/api.js?v=202607232105"></script>
     <script src="/static/js/services/audioEngine.js?v=202607232105"></script>