I've created a rounded corner button and in IE9 the gradient background is not rounded:

Here is the CSS:
.search button {
    padding: 10px;
    font-family: "OpenSansSemibold", "Helvetica", Arial, sans-serif;
    font-size: 16px;
    display: inline-block;
    outline: none;
    cursor: pointer;
    text-align: center;
    text-decoration: none;
    padding: .5em 2em .55em;
    text-shadow: 0 1px 1px rgba(0,0,0,.3);
    -webkit-border-radius: .5em; 
    -moz-border-radius: .5em;
    border-radius: .5em;
    -webkit-box-shadow: 0 1px 2px rgba(0,0,0,.2);
    -moz-box-shadow: 0 1px 2px rgba(0,0,0,.2);
    box-shadow: 0 1px 2px rgba(0,0,0,.2);
    color: #fef4e9;
    border: solid 1px #da7c0c;
    background: #f78d1d;
    background: -webkit-gradient(linear, left top, left bottom, from(#faa51a), to(#f47a20));
    background: -moz-linear-gradient(top,  #faa51a,  #f47a20);
    filter:  progid:DXImageTransform.Microsoft.gradient(startColorstr='#faa51a', endColorstr='#f47a20');
}
How can I fix this?
 
     
    