diff --git a/modules/taxonomy_manager_merge/js/tree.js b/modules/taxonomy_manager_merge/js/tree.js
index ae69979e7dde2b0afadd9f4160f48f3d55d697da..41b318453dd0547f83b43d2e65dca985c3a08229 100644
--- a/modules/taxonomy_manager_merge/js/tree.js
+++ b/modules/taxonomy_manager_merge/js/tree.js
@@ -9,7 +9,7 @@
       document.addEventListener('taxonomy_manager-tree-select', function (event) {
         let data = event.detail || {};
 
-        if (data.tree.getSelectedNodes().length < 2) {
+        if (data.tree.getSelectedNodes().length < 1) {
           // Disable the button if less the two terms are selected.
           document.getElementById('edit-merge').disabled = true;
         } else {