diff --git a/c3.js b/c3.js
index 9c15ed1..21ab1b4 100644
--- a/c3.js
+++ b/c3.js
@@ -1258,7 +1258,7 @@
                 .attr("height", __axis_rotated ? regionWidth : height)
                 .style("opacity", function(d){ return typeof d.opacity !== 'undefined' ? d.opacity : .1 })
             mainRegion.exit().transition().duration(withTransition ? 250 : 0)
-                .attr("opacity", 0)
+                .style("opacity", 0)
                 .remove()
         }