diff --git a/build/reactable.js b/build/reactable.js
index 7671bed2..4ceb1ddb 100644
--- a/build/reactable.js
+++ b/build/reactable.js
@@ -105,7 +105,7 @@ window.ReactDOM["default"] = window.ReactDOM;
     exports.stringable = stringable;
 
     function stringable(thing) {
-        return thing !== null && typeof thing !== 'undefined' && typeof (thing.toString === 'function');
+        return thing !== null && typeof thing !== 'undefined' && typeof thing.toString === 'function';
     }
 });
 
diff --git a/lib/reactable/lib/stringable.js b/lib/reactable/lib/stringable.js
index e52bd666..ee5f6818 100644
--- a/lib/reactable/lib/stringable.js
+++ b/lib/reactable/lib/stringable.js
@@ -6,5 +6,5 @@ Object.defineProperty(exports, '__esModule', {
 exports.stringable = stringable;
 
 function stringable(thing) {
-    return thing !== null && typeof thing !== 'undefined' && typeof (thing.toString === 'function');
+    return thing !== null && typeof thing !== 'undefined' && typeof thing.toString === 'function';
 }
diff --git a/src/reactable/lib/stringable.jsx b/src/reactable/lib/stringable.jsx
index c5aa8b9c..fbf7e26a 100644
--- a/src/reactable/lib/stringable.jsx
+++ b/src/reactable/lib/stringable.jsx
@@ -1,5 +1,5 @@
 export function stringable(thing) {
     return thing !== null &&
         typeof(thing) !== 'undefined' &&
-        typeof(thing.toString === 'function');
+        (typeof thing.toString) === 'function';
 }