diff --git a/app/assets/javascripts/discourse/helpers/plugin-outlet.js.es6 b/app/assets/javascripts/discourse/helpers/plugin-outlet.js.es6
index 13acb784e96..6e8bbcc0d98 100644
--- a/app/assets/javascripts/discourse/helpers/plugin-outlet.js.es6
+++ b/app/assets/javascripts/discourse/helpers/plugin-outlet.js.es6
@@ -62,11 +62,18 @@ function findOutlets(collection, callback) {
         }
       }
 
-      const segments = res.split("/"),
-            outletName = segments[segments.length-2],
-            uniqueName = segments[segments.length-1];
+      const segments = res.split("/");
+      const outletName = segments[segments.length-2];
+      const uniqueName = segments[segments.length-1];
+
+      const dashedName = outletName.replace(/_/g, '-');
+      if (dashedName !== outletName) {
+        Ember.warn("DEPRECATION: You need to use dashes in outlet names, not underscores");
+        callback(dashedName, res, uniqueName);
+      } else {
+        callback(outletName, res, uniqueName);
+      }
 
-      callback(outletName, res, uniqueName);
     }
   });
 }
diff --git a/app/assets/javascripts/discourse/templates/user/preferences.hbs b/app/assets/javascripts/discourse/templates/user/preferences.hbs
index 44d59c94c7a..8b622f65045 100644
--- a/app/assets/javascripts/discourse/templates/user/preferences.hbs
+++ b/app/assets/javascripts/discourse/templates/user/preferences.hbs
@@ -216,7 +216,7 @@
         {{preference-checkbox labelKey="user.edit_history_public" checked=model.edit_history_public}}
       {{/unless}}
 
-      {{plugin-outlet "user_custom_preferences"}}
+      {{plugin-outlet "user-custom-preferences"}}
     </div>
 
     <div class="control-group category">