diff --git a/specs/Modal.helpers.spec.js b/specs/Modal.helpers.spec.js
new file mode 100644
index 00000000..50931619
--- /dev/null
+++ b/specs/Modal.helpers.spec.js
@@ -0,0 +1,110 @@
+/* eslint-env mocha */
+import "should";
+import tabbable from "../src/helpers/tabbable";
+import "sinon";
+
+export default () => {
+  describe("tabbable", () => {
+    describe("without tabbable descendents", () => {
+      it("returns an empty array", () => {
+        const elem = document.createElement("div");
+        tabbable(elem).should.deepEqual([]);
+      });
+    });
+
+    describe("with tabbable descendents", () => {
+      let elem;
+      beforeEach(() => {
+        elem = document.createElement("div");
+        document.body.appendChild(elem);
+      });
+
+      afterEach(() => {
+        document.body.removeChild(elem);
+      });
+
+      it("includes descendent tabbable inputs", () => {
+        const input = document.createElement("input");
+        elem.appendChild(input);
+        tabbable(elem).should.containEql(input);
+      });
+
+      it("includes tabbable non-input elements", () => {
+        const div = document.createElement("div");
+        div.tabIndex = 1;
+        elem.appendChild(div);
+        tabbable(elem).should.containEql(div);
+      });
+
+      it("includes links with an href", () => {
+        const a = document.createElement("a");
+        a.href = "foobar";
+        a.innerHTML = "link";
+        elem.appendChild(a);
+        tabbable(elem).should.containEql(a);
+      });
+
+      it("excludes links without an href or a tabindex", () => {
+        const a = document.createElement("a");
+        elem.appendChild(a);
+        tabbable(elem).should.not.containEql(a);
+      });
+
+      it("excludes descendent inputs if they are not tabbable", () => {
+        const input = document.createElement("input");
+        input.tabIndex = -1;
+        elem.appendChild(input);
+        tabbable(elem).should.not.containEql(input);
+      });
+
+      it("excludes descendent inputs if they are disabled", () => {
+        const input = document.createElement("input");
+        input.disabled = true;
+        elem.appendChild(input);
+        tabbable(elem).should.not.containEql(input);
+      });
+
+      it("excludes descendent inputs if they are not displayed", () => {
+        const input = document.createElement("input");
+        input.style.display = "none";
+        elem.appendChild(input);
+        tabbable(elem).should.not.containEql(input);
+      });
+
+      it("excludes descendent inputs with 0 width and height", () => {
+        const input = document.createElement("input");
+        input.style.width = "0";
+        input.style.height = "0";
+        input.style.border = "0";
+        input.style.padding = "0";
+        elem.appendChild(input);
+        tabbable(elem).should.not.containEql(input);
+      });
+
+      it("excludes descendents with hidden parents", () => {
+        const input = document.createElement("input");
+        elem.style.display = "none";
+        elem.appendChild(input);
+        tabbable(elem).should.not.containEql(input);
+      });
+
+      it("excludes inputs with parents that have zero width and height", () => {
+        const input = document.createElement("input");
+        elem.style.width = "0";
+        elem.style.height = "0";
+        elem.style.overflow = "hidden";
+        elem.appendChild(input);
+        tabbable(elem).should.not.containEql(input);
+      });
+
+      it("includes inputs visible because of overflow == visible", () => {
+        const input = document.createElement("input");
+        elem.style.width = "0";
+        elem.style.height = "0";
+        elem.style.overflow = "visible";
+        elem.appendChild(input);
+        tabbable(elem).should.containEql(input);
+      });
+    });
+  });
+};
diff --git a/specs/Modal.spec.js b/specs/Modal.spec.js
index 6aed4586..22ef069f 100644
--- a/specs/Modal.spec.js
+++ b/specs/Modal.spec.js
@@ -1,5 +1,4 @@
 /* eslint-env mocha */
-import "should";
 import should from "should";
 import React, { Component } from "react";
 import ReactDOM from "react-dom";
diff --git a/specs/index.js b/specs/index.js
index f640547c..b9e03b91 100644
--- a/specs/index.js
+++ b/specs/index.js
@@ -3,7 +3,9 @@
 import ModalState from "./Modal.spec";
 import ModalEvents from "./Modal.events.spec";
 import ModalStyle from "./Modal.style.spec";
+import ModalHelpers from "./Modal.helpers.spec";
 
 describe("State", ModalState);
 describe("Style", ModalStyle);
 describe("Events", ModalEvents);
+describe("Helpers", ModalHelpers);
diff --git a/src/helpers/tabbable.js b/src/helpers/tabbable.js
index dc3c50b4..e1aa3936 100644
--- a/src/helpers/tabbable.js
+++ b/src/helpers/tabbable.js
@@ -12,17 +12,24 @@
 
 const tabbableNode = /input|select|textarea|button|object/;
 
-function hidden(el) {
-  return (
-    (el.offsetWidth <= 0 && el.offsetHeight <= 0) || el.style.display === "none"
-  );
+function hidesContents(element) {
+  const zeroSize = element.offsetWidth <= 0 && element.offsetHeight <= 0;
+
+  // If the node is empty, this is good enough
+  if (zeroSize && !element.innerHTML) return true;
+
+  // Otherwise we need to check some styles
+  const style = window.getComputedStyle(element);
+  return zeroSize
+    ? style.getPropertyValue("overflow") !== "visible"
+    : style.getPropertyValue("display") == "none";
 }
 
 function visible(element) {
   let parentElement = element;
   while (parentElement) {
     if (parentElement === document.body) break;
-    if (hidden(parentElement)) return false;
+    if (hidesContents(parentElement)) return false;
     parentElement = parentElement.parentNode;
   }
   return true;