diff --git a/core/block.js b/core/block.js
index d3193fb74..4e7f65299 100644
--- a/core/block.js
+++ b/core/block.js
@@ -402,7 +402,7 @@ Blockly.Block.prototype.unplugFromStack_ = function(opt_healStack) {
     // Disconnect the next statement.
     var nextTarget = this.nextConnection.targetConnection;
     nextTarget.disconnect();
-    // Shouldn't checkType happen earlier?
+    // TODO (#1994): Check types before unplugging.
     if (previousTarget && previousTarget.checkType_(nextTarget)) {
       // Attach the next statement to the previous statement.
       previousTarget.connect(nextTarget);