1 files changed, 11 insertions, 4 deletions
diff --git a/railties/lib/rails/api/task.rb b/railties/lib/rails/api/task.rb
index 3e7223f075..81d6dea792 100644
--- a/railties/lib/rails/api/task.rb
+++ b/railties/lib/rails/api/task.rb
@@ -69,12 +69,11 @@ module Rails
 
         options << '-m'  << api_main
         options << '-e'  << 'UTF-8'
-        options << '-f'  << 'sdoc'
-        options << '-T'  << 'rails'
 
         configure_rdoc_files
 
         before_running_rdoc do
+          load_and_configure_sdoc
           setup_horo_variables
         end
       end
@@ -84,6 +83,15 @@ module Rails
         # no-op
       end
 
+      def load_and_configure_sdoc
+        require 'sdoc'
+        options << '-f'  << 'sdoc'
+        options << '-T'  << 'rails'
+      rescue LoadError
+        $stderr.puts %(Unable to load SDoc, please add\n\n    gem 'sdoc', require: false\n\nto the Gemfile.)
+        exit 1
+      end
+
       def configure_rdoc_files
         rdoc_files.include(api_main)
 
@@ -111,9 +119,8 @@ module Rails
     end
 
     class RepoTask < Task
-      def initialize(name)
+      def load_and_configure_sdoc
         super
-
         options << '-g' # link to GitHub, SDoc flag
       end