diff --git a/examples/splat-painter/index.html b/examples/splat-painter/index.html
index 0e56cf5c..d36bdf05 100644
--- a/examples/splat-painter/index.html
+++ b/examples/splat-painter/index.html
@@ -487,7 +487,7 @@
           
           // Now export the PackedSplats to SPZ
           console.log("Writing splats to SPZ...");
-          const { fileBytes: spzBytes } = writeSpz(newPackedSplats, ioOptions.maxSh, ioOptions.fractionalBits);
+          const { fileBytes: spzBytes } = await writeSpz(newPackedSplats, ioOptions.maxSh, ioOptions.fractionalBits);
 
           console.log("Creating download...");
           const blob = new Blob([spzBytes], { type: "application/octet-stream" });
diff --git a/src/spz.ts b/src/spz.ts
index 03d36e22..299beda8 100644
--- a/src/spz.ts
+++ b/src/spz.ts
@@ -99,16 +99,18 @@ export function writeSpz(
   splats: PackedSplats | ExtSplats,
   maxSh?: number,
   fractionalBits?: number,
-): { fileBytes: Uint8Array };
+): Promise<{ fileBytes: Uint8Array }>;
 export function writeSpz(
   splats: PackedSplats | ExtSplats,
   options?: WriteSpzOptions,
-): { fileBytes: Uint8Array };
-export function writeSpz(
+): Promise<{ fileBytes: Uint8Array }>;
+export async function writeSpz(
   splats: PackedSplats | ExtSplats,
   maxShOrOptions?: number | WriteSpzOptions,
   fractionalBits?: number,
 ) {
+  await wasm.initialization;
+
   const options: WriteSpzOptions =
     typeof maxShOrOptions === "number"
       ? { maxSh: maxShOrOptions, fractionalBits }