diff --git a/activemodel/lib/active_model/naming.rb b/activemodel/lib/active_model/naming.rb
index ea4f9341c6..43d11b1b08 100644
--- a/activemodel/lib/active_model/naming.rb
+++ b/activemodel/lib/active_model/naming.rb
@@ -256,11 +256,11 @@ def self.uncountable?(record_or_class)
     # Returns string to use while generating route names. It differs for
     # namespaced models regarding whether it's inside isolated engine.
     #
-    # For isolated engine:
-    # ActiveModel::Naming.route_key(Blog::Post) #=> post
+    #   # For isolated engine:
+    #   ActiveModel::Naming.route_key(Blog::Post) #=> post
     #
-    # For shared engine:
-    # ActiveModel::Naming.route_key(Blog::Post) #=> blog_post
+    #   # For shared engine:
+    #   ActiveModel::Naming.route_key(Blog::Post) #=> blog_post
     def self.singular_route_key(record_or_class)
       model_name_from_record_or_class(record_or_class).singular_route_key
     end
@@ -268,11 +268,11 @@ def self.singular_route_key(record_or_class)
     # Returns string to use while generating route names. It differs for
     # namespaced models regarding whether it's inside isolated engine.
     #
-    # For isolated engine:
-    # ActiveModel::Naming.route_key(Blog::Post) #=> posts
+    #   # For isolated engine:
+    #   ActiveModel::Naming.route_key(Blog::Post) #=> posts
     #
-    # For shared engine:
-    # ActiveModel::Naming.route_key(Blog::Post) #=> blog_posts
+    #   # For shared engine:
+    #   ActiveModel::Naming.route_key(Blog::Post) #=> blog_posts
     #
     # The route key also considers if the noun is uncountable and, in
     # such cases, automatically appends _index.
@@ -283,11 +283,11 @@ def self.route_key(record_or_class)
     # Returns string to use for params names. It differs for
     # namespaced models regarding whether it's inside isolated engine.
     #
-    # For isolated engine:
-    # ActiveModel::Naming.param_key(Blog::Post) #=> post
+    #   # For isolated engine:
+    #   ActiveModel::Naming.param_key(Blog::Post) #=> post
     #
-    # For shared engine:
-    # ActiveModel::Naming.param_key(Blog::Post) #=> blog_post
+    #   # For shared engine:
+    #   ActiveModel::Naming.param_key(Blog::Post) #=> blog_post
     def self.param_key(record_or_class)
       model_name_from_record_or_class(record_or_class).param_key
     end