diff --git a/index.js b/index.js
index b5507ce..d1e177b 100644
--- a/index.js
+++ b/index.js
@@ -3,5 +3,9 @@
 const bindings = require('bindings')('ced.node')
 
 module.exports = buf => {
+  if (!Buffer.isBuffer(buf)) {
+    throw new TypeError('Expected a buffer')
+  }
+
   return bindings.detectEncoding(buf)
 }
diff --git a/test.js b/test.js
index e0b0c4b..b84ae19 100644
--- a/test.js
+++ b/test.js
@@ -10,3 +10,9 @@ test('detects ASCII', t => {
   const buf = Buffer.from('tést', 'ascii')
   t.is(ced(buf), 'ASCII')
 })
+
+test('throws a TypeError if the argument is not a buffer', t => {
+  t.throws(() => {
+    ced('tést')
+  }, TypeError)
+})