diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index c508512ff6cd6..2da3b344baa26 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -486,7 +486,7 @@ def mailer_name
       self.class.mailer_name
     end
 
-    # Allows you to pass random and unusual headers to the new +Mail::Message+ object
+    # Allows you to pass random and unusual headers to the new <tt>Mail::Message</tt> object
     # which will add them to itself.
     #
     #   headers['X-Special-Domain-Specific-Header'] = "SecretValue"
diff --git a/actionpack/lib/action_controller/metal/params_wrapper.rb b/actionpack/lib/action_controller/metal/params_wrapper.rb
index fa760f265804c..17e2db74d4966 100644
--- a/actionpack/lib/action_controller/metal/params_wrapper.rb
+++ b/actionpack/lib/action_controller/metal/params_wrapper.rb
@@ -66,7 +66,7 @@ module ActionController
   #     class Admin::UsersController < ApplicationController
   #     end
   #
-  # will try to check if +Admin::User+ or +User+ model exists, and use it to
+  # will try to check if <tt>Admin::User</tt> or +User+ model exists, and use it to
   # determine the wrapper key respectively. If both models don't exist,
   # it will then fallback to use +user+ as the key.
   module ParamsWrapper
diff --git a/actionpack/lib/action_controller/metal/streaming.rb b/actionpack/lib/action_controller/metal/streaming.rb
index 52aaed0ed456b..eeb37db2e7300 100644
--- a/actionpack/lib/action_controller/metal/streaming.rb
+++ b/actionpack/lib/action_controller/metal/streaming.rb
@@ -139,17 +139,17 @@ module ActionController #:nodoc:
   # session or flash after the template starts rendering will not propagate
   # to the client.
   #
-  # If you try to modify cookies, session or flash, an +ActionDispatch::ClosedError+
+  # If you try to modify cookies, session or flash, an <tt>ActionDispatch::ClosedError</tt>
   # will be raised, showing those objects are closed for modification.
   #
   # == Middlewares
   #
   # Middlewares that need to manipulate the body won't work with streaming.
   # You should disable those middlewares whenever streaming in development
-  # or production. For instance, +Rack::Bug+ won't work when streaming as it
+  # or production. For instance, <tt>Rack::Bug</tt> won't work when streaming as it
   # needs to inject contents in the HTML body.
   #
-  # Also +Rack::Cache+ won't work with streaming as it does not support
+  # Also <tt>Rack::Cache</tt> won't work with streaming as it does not support
   # streaming bodies yet. Whenever streaming Cache-Control is automatically
   # set to "no-cache".
   #
diff --git a/activemodel/lib/active_model/serialization.rb b/activemodel/lib/active_model/serialization.rb
index a5828476b16e8..4403ef060b245 100644
--- a/activemodel/lib/active_model/serialization.rb
+++ b/activemodel/lib/active_model/serialization.rb
@@ -34,7 +34,7 @@ module ActiveModel
   #
   # Most of the time though, you will want to include the JSON or XML
   # serializations. Both of these modules automatically include the
-  # +ActiveModel::Serialization+ module, so there is no need to explicitly
+  # <tt>ActiveModel::Serialization</tt> module, so there is no need to explicitly
   # include it.
   #
   # A minimal implementation including XML and JSON would be:
diff --git a/railties/lib/rails/configuration.rb b/railties/lib/rails/configuration.rb
index d8ca6cbd217e2..493eacdc5a64d 100644
--- a/railties/lib/rails/configuration.rb
+++ b/railties/lib/rails/configuration.rb
@@ -16,7 +16,7 @@ module Configuration
     #
     #     config.middleware.use Magical::Unicorns
     #
-    # This will put the +Magical::Unicorns+ middleware on the end of the stack.
+    # This will put the <tt>Magical::Unicorns</tt> middleware on the end of the stack.
     # You can use +insert_before+ if you wish to add a middleware before another:
     #
     #     config.middleware.insert_before ActionDispatch::Head, Magical::Unicorns
diff --git a/railties/lib/rails/paths.rb b/railties/lib/rails/paths.rb
index dd1790299d3c8..9b4a69f19f6a1 100644
--- a/railties/lib/rails/paths.rb
+++ b/railties/lib/rails/paths.rb
@@ -8,7 +8,7 @@ module Paths
     #   root.add "app/controllers", :eager_load => true
     #
     # The command above creates a new root object and add "app/controllers" as a path.
-    # This means we can get a +Rails::Paths::Path+ object back like below:
+    # This means we can get a <tt>Rails::Paths::Path</tt> object back like below:
     #
     #   path = root["app/controllers"]
     #   path.eager_load?               # => true