diff --git a/src/mol-io/reader/_spec/ccp4.spec.ts b/src/mol-io/reader/_spec/ccp4.spec.ts
index 0b3a23859da692e417edb8c2975bdcc881ef5813..fc57da2ad58e4c009ed85cc338dbf22b557c2e81 100644
--- a/src/mol-io/reader/_spec/ccp4.spec.ts
+++ b/src/mol-io/reader/_spec/ccp4.spec.ts
@@ -7,7 +7,7 @@
 import CCP4 from '../ccp4/parser'
 import { FileHandle } from '../../common/file-handle';
 
-const ccp4Buffer = new Uint8Array([])
+const ccp4Buffer = new Uint8Array(4 * 64)
 
 describe('ccp4 reader', () => {
     it('basic', async () => {