diff --git a/js/molarity/view/SoluteComboBox.js b/js/molarity/view/SoluteComboBox.js
index d8288da5..c9f95657 100644
--- a/js/molarity/view/SoluteComboBox.js
+++ b/js/molarity/view/SoluteComboBox.js
@@ -35,6 +35,7 @@ define( function( require ) {
     options = _.extend( {
       labelNode: new Text( StringUtils.format( pattern0LabelString, soluteString ), { font: new PhetFont( 22 ) } ), // 'Solute' label
       listPosition: 'above',
+      cornerRadius: 8,
       xMargin: 16,
       yMargin: 16,
       highlightFill: 'rgb( 218, 255, 255 )',