diff --git a/lib/index.js b/lib/index.js
index 0803058..b531720 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -514,6 +514,10 @@ MarkdownIt.prototype.use = function (plugin /*, params, ... */) {
  * and then pass updated object to renderer.
  **/
 MarkdownIt.prototype.parse = function (src, env) {
+  if (typeof src !== 'string') {
+    throw new Error('Input data should be a String');
+  }
+
   var state = new this.core.State(src, this, env);
 
   this.core.process(state);
diff --git a/test/misc.js b/test/misc.js
index 0497642..5b20392 100644
--- a/test/misc.js
+++ b/test/misc.js
@@ -145,6 +145,15 @@ describe('API', function () {
     assert(md.renderInline('_foo_'), '<em>foo</em>');
   });
 
+  it('input type check', function () {
+    var md = markdownit();
+
+    assert.throws(
+      function () { md.render(null); },
+      /Input data should be a String/
+    );
+  });
+
 });