diff --git a/es6-shim.js b/es6-shim.js
index 369ebba6..95ef318f 100644
--- a/es6-shim.js
+++ b/es6-shim.js
@@ -613,7 +613,13 @@
     },
 
     includes: function includes(searchString) {
-      var position = arguments.length > 1 ? arguments[1] : void 0;
+      if (Type.regex(searchString)) {
+        throw new TypeError('"includes" does not accept a RegExp');
+      }
+      var position;
+      if (arguments.length > 1) {
+        position = arguments[1];
+      }
       // Somehow this trick makes method 100% compat with the spec.
       return _indexOf(this, searchString, position) !== -1;
     },
diff --git a/test/string.js b/test/string.js
index cab71e7e..a1feae5d 100644
--- a/test/string.js
+++ b/test/string.js
@@ -315,6 +315,10 @@ var runStringTests = function () {
         testObjectCoercible('includes');
       });
 
+      it('throws a TypeError when given a regex', function () {
+        expect(function () { 'foo'.includes(/a/g); }).to['throw'](TypeError);
+      });
+
       it('should be truthy on correct results', function () {
         expect('test'.includes('es')).to.equal(true);
         expect('abc'.includes('a')).to.equal(true);