// TODO(danvk): remove this use of a private API
var xOptView = g.optionsViewForAxis_('x');
var xvf = xOptView('valueFormatter');
- html = xvf(x, xOptView, labels[0], g) + ":";
+ html = xvf(x, xOptView, labels[0], g);
+ if(html) {
+ html += ':';
+ }
var yOptViews = [];
var num_axes = g.numAxes();