diff --git a/test/unit/libvips.js b/test/unit/libvips.js
index dee38d175..3e013518f 100644
--- a/test/unit/libvips.js
+++ b/test/unit/libvips.js
@@ -147,20 +147,23 @@ describe('libvips binaries', function () {
 
   describe('yarn locator hash', () => {
     it('known platform', () => {
+      const cc = process.env.CC;
+      delete process.env.CC;
       process.env.npm_config_platform = 'linux';
       process.env.npm_config_arch = 's390x';
+      process.env.npm_config_libc = '';
       const locatorHash = libvips.yarnLocator();
       assert.strictEqual(locatorHash, '86cc8ee6e4');
       delete process.env.npm_config_platform;
       delete process.env.npm_config_arch;
+      delete process.env.npm_config_libc;
+      process.env.CC = cc;
     });
     it('unknown platform', () => {
       process.env.npm_config_platform = 'unknown-platform';
-      process.env.npm_config_arch = 'unknown-arch';
       const locatorHash = libvips.yarnLocator();
       assert.strictEqual(locatorHash, '');
       delete process.env.npm_config_platform;
-      delete process.env.npm_config_arch;
     });
   });
 });