diff --git a/src/time-picker/clock.jsx b/src/time-picker/clock.jsx
index 42a69838ac759d..a6979a5396ef41 100644
--- a/src/time-picker/clock.jsx
+++ b/src/time-picker/clock.jsx
@@ -80,8 +80,8 @@ const Clock = React.createClass({
 
     if (this.props.format === 'ampm'){
       buttons = [
-        <ClockButton position="left" onTouchTap={this._setAffix.bind(this, "am")} selected={isAM} >{"AM"}</ClockButton>,
-        <ClockButton position="right" onTouchTap={this._setAffix.bind(this, "pm")} selected={!isAM} >{"PM"}</ClockButton>,
+        <ClockButton key="AM" position="left" onTouchTap={this._setAffix.bind(this, "am")} selected={isAM} >{"AM"}</ClockButton>,
+        <ClockButton key="PM" position="right" onTouchTap={this._setAffix.bind(this, "pm")} selected={!isAM} >{"PM"}</ClockButton>,
       ];
     }
     return buttons;