diff --git a/app/assets/javascripts/discourse/components/category-select-box.js.es6 b/app/assets/javascripts/discourse/components/category-select-box.js.es6
index 9be9c3e689f..e0ec28846e5 100644
--- a/app/assets/javascripts/discourse/components/category-select-box.js.es6
+++ b/app/assets/javascripts/discourse/components/category-select-box.js.es6
@@ -61,6 +61,16 @@ export default SelectBoxComponent.extend({
     this.set("content", filteredCategories);
   },
 
+  @on("didRender")
+  _bindComposerResizing() {
+    this.appEvents.on("composer:resized", this, this.applyDirection);
+  },
+
+  @on("willDestroyElement")
+  _unbindComposerResizing() {
+    this.appEvents.off("composer:resized");
+  },
+
   @on("init")
   @observes("site.sortedCategories")
   _updateCategories() {
diff --git a/app/assets/javascripts/discourse/components/select-box.js.es6 b/app/assets/javascripts/discourse/components/select-box.js.es6
index b6761cbdee8..fa160ddc1bd 100644
--- a/app/assets/javascripts/discourse/components/select-box.js.es6
+++ b/app/assets/javascripts/discourse/components/select-box.js.es6
@@ -136,7 +136,7 @@ export default Ember.Component.extend({
       this._bindTab();
 
       Ember.run.schedule('afterRender', () => {
-        this._applyDirection();
+        this.applyDirection();
         this._positionSelectBoxWrapper();
       });
     } else {
@@ -272,7 +272,7 @@ export default Ember.Component.extend({
     });
   },
 
-  _applyDirection() {
+  applyDirection() {
     this.$().removeClass("is-reversed");
 
     const offsetTop = this.$()[0].getBoundingClientRect().top;