diff --git a/browser.js b/browser.js
index ab96170..7886210 100644
--- a/browser.js
+++ b/browser.js
@@ -5,11 +5,16 @@
 "use strict";
 
 require("es6-promise").polyfill();
+var assert = require("assert");
 var EC = require("elliptic").ec;
 
 var ec = new EC("secp256k1");
 
 exports.getPublic = function(privateKey) {
+  // `elliptic` doesn't have such checkings so we do it ourself. We
+  // should always ensure that library user doesn't try to do something
+  // dumb.
+  assert(privateKey.length === 32, "Bad private key");
   // XXX(Kagami): `elliptic.utils.encode` returns array for every
   // encoding except `hex`.
   return new Buffer(ec.keyPair(privateKey).getPublic("arr"));
diff --git a/test.js b/test.js
index d6ffce8..e6199b0 100644
--- a/test.js
+++ b/test.js
@@ -16,6 +16,7 @@ describe("Key convertion", function() {
 
   it("should throw on invalid private key", function() {
     expect(eccrypto.getPublic.bind(null, Buffer("00", "hex"))).to.throw(Error);
+    expect(eccrypto.getPublic.bind(null, Buffer("test"))).to.throw(Error);
   });
 });