diff --git a/src/codecs/rotate/processor.ts b/src/codecs/rotate/processor.ts
index 6aa80081..0f795e51 100644
--- a/src/codecs/rotate/processor.ts
+++ b/src/codecs/rotate/processor.ts
@@ -1,23 +1,30 @@
 import wasmUrl from '../../../codecs/rotate/rotate.wasm';
 import { RotateOptions, RotateModuleInstance } from './processor-meta';
 
+const instancePromise = (WebAssembly as any).instantiateStreaming(fetch(wasmUrl));
+
 export async function rotate(
   data: ImageData,
   opts: RotateOptions,
 ): Promise<ImageData> {
-  const flipDimensions = opts.rotate % 180 !== 0;
+  const { instance } = (await instancePromise) as {instance: RotateModuleInstance};
+
   // Number of wasm memory pages (á 64KiB) needed to store the image twice.
   const bytesPerImage = data.width * data.height * 4;
-  const numPagesNeeded = Math.ceil(bytesPerImage * 2 / (64 * 1024));
-  const { instance } = (await (WebAssembly as any).instantiateStreaming(
-    fetch(wasmUrl),
-  )) as { instance: RotateModuleInstance };
+  const numPagesNeeded = Math.ceil(bytesPerImage * 2 / (64 * 1024) + 4);
+  // Only count full pages, just to be safe.
+  const numPagesAvailable = Math.floor(instance.exports.memory.buffer.byteLength / (64 * 1024));
+  const additionalPagesToAllocate = numPagesNeeded - numPagesAvailable;
 
-  instance.exports.memory.grow(numPagesNeeded);
+  if (additionalPagesToAllocate > 0) {
+    instance.exports.memory.grow(additionalPagesToAllocate);
+  }
   const view = new Uint8ClampedArray(instance.exports.memory.buffer);
   view.set(data.data);
 
   instance.exports.rotate(data.width, data.height, opts.rotate);
+
+  const flipDimensions = opts.rotate % 180 !== 0;
   return new ImageData(
     view.slice(bytesPerImage, bytesPerImage * 2),
     flipDimensions ? data.height : data.width,