diff --git a/src/core/lib/Zstd.mjs b/src/core/lib/Zstd.mjs
index 6178307b..0c0b8e9e 100644
--- a/src/core/lib/Zstd.mjs
+++ b/src/core/lib/Zstd.mjs
@@ -22,7 +22,9 @@ let initPromise = null;
  */
 export function zstdInit() {
     if (!initPromise) {
-        const wasmUrl = `${self.docURL}/assets/zstd.wasm`;
+        const wasmUrl = typeof self !== "undefined" && self.docURL
+            ? `${self.docURL}/assets/zstd.wasm`
+            : undefined;
         initPromise = init(wasmUrl);
     }
     return initPromise;