diff --git a/binding.js b/binding.js
index 0ef7e57b..f600dec5 100644
--- a/binding.js
+++ b/binding.js
@@ -10,24 +10,15 @@ const semver = require('semver');
 const tar = require('tar');
 const detectLibc = require('detect-libc');
 
+const platform = require('./lib/platform');
+
 // Use NPM-provided environment variable where available, falling back to require-based method for Electron
 const minimumLibvipsVersion = process.env.npm_package_config_libvips || require('./package.json').config.libvips;
 
 const distBaseUrl = process.env.SHARP_DIST_BASE_URL || `https://github.com/lovell/sharp-libvips/releases/download/v${minimumLibvipsVersion}/`;
 
-const platform = process.env.npm_config_platform || process.platform;
-
-const arch = process.env.npm_config_arch || process.arch;
-
 // -- Helpers
 
-// Does this file exist?
-const isFile = function (file) {
-  try {
-    return fs.statSync(file).isFile();
-  } catch (err) {}
-};
-
 const unpack = function (tarPath, done) {
   const vendorPath = path.join(__dirname, 'vendor');
   fs.mkdirSync(vendorPath);
@@ -41,73 +32,68 @@ const unpack = function (tarPath, done) {
     .catch(error);
 };
 
-const platformId = function () {
-  const platformId = [platform];
-  if (arch === 'arm' || arch === 'armhf' || arch === 'arm64') {
-    const armVersion = (arch === 'arm64') ? '8' : process.env.npm_config_armv || process.config.variables.arm_version || '6';
-    platformId.push('armv' + armVersion);
-  } else {
-    platformId.push(arch);
-  }
-  return platformId.join('-');
-};
-
-// Error
 const error = function (msg) {
   if (msg instanceof Error) {
     msg = msg.message;
   }
-  process.stderr.write('ERROR: ' + msg + '\n');
+  process.stderr.write(`sharp: ${msg}\n`);
   process.exit(1);
 };
 
 // -- Binary downloaders
 
 module.exports.download_vips = function () {
-  // Has vips been installed locally?
-  const vipsHeaderPath = path.join(__dirname, 'vendor', 'include', 'vips', 'vips.h');
-  if (!isFile(vipsHeaderPath)) {
-    // Ensure Intel 64-bit or ARM
-    if (arch === 'ia32') {
-      error('Intel Architecture 32-bit systems require manual installation of libvips - please see http://sharp.dimens.io/page/install');
+  // Check for existing vendored binaries and verify platform matches
+  const currentPlatformId = platform();
+  try {
+    const vendorPlatformId = require(path.join(__dirname, 'vendor', 'platform.json'));
+    if (currentPlatformId === vendorPlatformId) {
+      return;
+    } else {
+      error(`'${vendorPlatformId}' binaries cannot be used on the '${currentPlatformId}' platform. Please remove the 'node_modules/sharp/vendor' directory and run 'npm install'.`);
     }
-    // Ensure glibc Linux
-    if (detectLibc.isNonGlibcLinux) {
-      error(`Use with ${detectLibc.family} libc requires manual installation of libvips - please see http://sharp.dimens.io/page/install`);
-    }
-    // Ensure glibc >= 2.13
-    if (detectLibc.family === detectLibc.GLIBC && detectLibc.version && semver.lt(`${detectLibc.version}.0`, '2.13.0')) {
-      error(`Use with glibc version ${detectLibc.version} requires manual installation of libvips - please see http://sharp.dimens.io/page/install`);
-    }
-    // Arch/platform-specific .tar.gz
-    const tarFilename = ['libvips', minimumLibvipsVersion, platformId()].join('-') + '.tar.gz';
-    // Download to per-process temporary file
-    const tarPathTemp = path.join(os.tmpdir(), process.pid + '-' + tarFilename);
-    const tmpFile = fs.createWriteStream(tarPathTemp).on('finish', function () {
-      unpack(tarPathTemp, function () {
-        // Attempt to remove temporary file
-        try {
-          fs.unlinkSync(tarPathTemp);
-        } catch (err) {}
-      });
-    });
-    const url = distBaseUrl + tarFilename;
-    const simpleGetOpt = {
-      url: url,
-      agent: caw(null, {
-        protocol: 'https'
-      })
-    };
-    simpleGet(simpleGetOpt, function (err, response) {
-      if (err) {
-        error('Download of ' + url + ' failed: ' + err.message);
-      }
-      if (response.statusCode !== 200) {
-        error(url + ' status code ' + response.statusCode);
-      }
-      response.pipe(tmpFile);
-    });
+  } catch (err) {}
+  // Ensure Intel 64-bit or ARM
+  const arch = process.env.npm_config_arch || process.arch;
+  if (arch === 'ia32') {
+    error('Intel Architecture 32-bit systems require manual installation of libvips - please see http://sharp.dimens.io/page/install');
   }
+  // Ensure glibc Linux
+  if (detectLibc.isNonGlibcLinux) {
+    error(`Use with ${detectLibc.family} libc requires manual installation of libvips - please see http://sharp.dimens.io/page/install`);
+  }
+  // Ensure glibc >= 2.13
+  if (detectLibc.family === detectLibc.GLIBC && detectLibc.version && semver.lt(`${detectLibc.version}.0`, '2.13.0')) {
+    error(`Use with glibc version ${detectLibc.version} requires manual installation of libvips - please see http://sharp.dimens.io/page/install`);
+  }
+  // Arch/platform-specific .tar.gz
+  const tarFilename = ['libvips', minimumLibvipsVersion, currentPlatformId].join('-') + '.tar.gz';
+  // Download to per-process temporary file
+  const tarPathTemp = path.join(os.tmpdir(), `${process.pid}-${tarFilename}`);
+  const tmpFile = fs.createWriteStream(tarPathTemp).on('finish', function () {
+    unpack(tarPathTemp, function () {
+      // Attempt to remove temporary file
+      try {
+        fs.unlinkSync(tarPathTemp);
+      } catch (err) {}
+    });
+  });
+  const url = distBaseUrl + tarFilename;
+  const simpleGetOpt = {
+    url: url,
+    agent: caw(null, {
+      protocol: 'https'
+    })
+  };
+  simpleGet(simpleGetOpt, function (err, response) {
+    if (err) {
+      error(`${url} download failed: ${err.message}`);
+    }
+    if (response.statusCode !== 200) {
+      error(`${url} download failed: status ${response.statusCode}`);
+    }
+    response.pipe(tmpFile);
+  });
 };
 
 module.exports.use_global_vips = function () {
diff --git a/lib/constructor.js b/lib/constructor.js
index b4364c6a..408ae049 100644
--- a/lib/constructor.js
+++ b/lib/constructor.js
@@ -6,8 +6,24 @@ const stream = require('stream');
 const events = require('events');
 const semver = require('semver');
 const is = require('./is');
+const platform = require('./platform');
 const sharp = require('../build/Release/sharp.node');
 
+// Vendor platform
+(function () {
+  let vendorPlatformId;
+  try {
+    vendorPlatformId = require('../vendor/platform.json');
+  } catch (err) {
+    return;
+  }
+  const currentPlatformId = platform();
+  /* istanbul ignore if */
+  if (currentPlatformId !== vendorPlatformId) {
+    throw new Error(`'${vendorPlatformId}' binaries cannot be used on the '${currentPlatformId}' platform. Please remove the 'node_modules/sharp/vendor' directory and run 'npm rebuild'.`);
+  }
+})();
+
 // Versioning
 let versions = {
   vips: sharp.libvipsVersion()
@@ -21,7 +37,7 @@ let versions = {
   }
   // Include versions of dependencies, if present
   try {
-    versions = require('../vendor/lib/versions.json');
+    versions = require('../vendor/versions.json');
   } catch (err) {}
 })();
 
diff --git a/lib/platform.js b/lib/platform.js
new file mode 100644
index 00000000..0d0722ba
--- /dev/null
+++ b/lib/platform.js
@@ -0,0 +1,15 @@
+'use strict';
+
+module.exports = function () {
+  const arch = process.env.npm_config_arch || process.arch;
+  const platform = process.env.npm_config_platform || process.platform;
+
+  const platformId = [platform];
+  if (arch === 'arm' || arch === 'armhf' || arch === 'arm64') {
+    const armVersion = (arch === 'arm64') ? '8' : process.env.npm_config_armv || process.config.variables.arm_version || '6';
+    platformId.push(`armv${armVersion}`);
+  } else {
+    platformId.push(arch);
+  }
+  return platformId.join('-');
+};
diff --git a/test/unit/platform.js b/test/unit/platform.js
new file mode 100644
index 00000000..87454c78
--- /dev/null
+++ b/test/unit/platform.js
@@ -0,0 +1,47 @@
+'use strict';
+
+const assert = require('assert');
+const platform = require('../../lib/platform');
+
+describe('Platform-detection', function () {
+  it('Can override arch with npm_config_arch', function () {
+    process.env.npm_config_arch = 'test';
+    assert.strictEqual('test', platform().split('-')[1]);
+    delete process.env.npm_config_arch;
+  });
+
+  it('Can override platform with npm_config_platform', function () {
+    process.env.npm_config_platform = 'test';
+    assert.strictEqual('test', platform().split('-')[0]);
+    delete process.env.npm_config_platform;
+  });
+
+  it('Can override ARM version via npm_config_armv', function () {
+    process.env.npm_config_arch = 'arm';
+    process.env.npm_config_armv = 'test';
+    assert.strictEqual('armvtest', platform().split('-')[1]);
+    delete process.env.npm_config_armv;
+    delete process.env.npm_config_arch;
+  });
+
+  it('Can detect ARM version via process.config', function () {
+    process.env.npm_config_arch = 'armhf';
+    const armVersion = process.config.variables.arm_version;
+    process.config.variables.arm_version = 'test';
+    assert.strictEqual('armvtest', platform().split('-')[1]);
+    process.config.variables.arm_version = armVersion;
+    delete process.env.npm_config_arch;
+  });
+
+  it('Defaults to ARMv6 for 32-bit', function () {
+    process.env.npm_config_arch = 'arm';
+    assert.strictEqual('armv6', platform().split('-')[1]);
+    delete process.env.npm_config_arch;
+  });
+
+  it('Defaults to ARMv8 for 64-bit', function () {
+    process.env.npm_config_arch = 'arm64';
+    assert.strictEqual('armv8', platform().split('-')[1]);
+    delete process.env.npm_config_arch;
+  });
+});