diff --git a/core/rendered_connection.js b/core/rendered_connection.js
index c68dc490d..76c63289b 100644
--- a/core/rendered_connection.js
+++ b/core/rendered_connection.js
@@ -180,16 +180,14 @@ Blockly.RenderedConnection.prototype.tighten_ = function() {
  * Find the closest compatible connection to this connection.
  * All parameters are in workspace units.
  * @param {number} maxLimit The maximum radius to another connection.
- * @param {number} dx Horizontal offset between this connection's location
- *     in the database and the current location (as a result of dragging).
- * @param {number} dy Vertical offset between this connection's location
+ * @param {!goog.math.Coordinate} dxy Offset between this connection's location
  *     in the database and the current location (as a result of dragging).
  * @return {!{connection: ?Blockly.Connection, radius: number}} Contains two
  *     properties: 'connection' which is either another connection or null,
  *     and 'radius' which is the distance.
  */
-Blockly.RenderedConnection.prototype.closest = function(maxLimit, dx, dy) {
-  return this.dbOpposite_.searchForClosest(this, maxLimit, dx, dy);
+Blockly.RenderedConnection.prototype.closest = function(maxLimit, dxy) {
+  return this.dbOpposite_.searchForClosest(this, maxLimit, dxy);
 };
 
 /**