diff --git a/lib/jekyll/cleaner.rb b/lib/jekyll/cleaner.rb
index c578c9b8..1786a317 100644
--- a/lib/jekyll/cleaner.rb
+++ b/lib/jekyll/cleaner.rb
@@ -49,7 +49,7 @@ module Jekyll
       #
       # Returns a Set with the directory paths
       def new_dirs
-        new_files.flat_map { |file| parent_dirs(file) }.to_set
+        new_files.map { |file| parent_dirs(file) }.flatten.to_set
       end
 
       # Private: The list of parent directories of a given file
@@ -76,7 +76,7 @@ module Jekyll
       #
       # Returns a Set with the directory paths
       def keep_dirs
-        site.keep_files.flat_map { |file| parent_dirs(File.join(site.dest, file)) }.to_set
+        site.keep_files.map { |file| parent_dirs(File.join(site.dest, file)) }.flatten.to_set
       end
 
       # Private: Creates a regular expression from the config's keep_files array
diff --git a/lib/jekyll/post.rb b/lib/jekyll/post.rb
index f816e165..68b85acb 100644
--- a/lib/jekyll/post.rb
+++ b/lib/jekyll/post.rb
@@ -115,7 +115,7 @@ module Jekyll
     #
     # Returns the post title
     def title
-      data.fetch("title") { titleized_slug }
+      data.fetch('title') { titleized_slug }
     end
 
     # Turns the post slug into a suitable title
diff --git a/lib/jekyll/url.rb b/lib/jekyll/url.rb
index 8773e018..56173de6 100644
--- a/lib/jekyll/url.rb
+++ b/lib/jekyll/url.rb
@@ -46,24 +46,23 @@ module Jekyll
     # Returns the _unsanitizied_ String URL
     def generate_url
       @placeholders.inject(@template) do |result, token|
-        result.tr(":#{token.first}", self.class.escape_path(token.last))
+        break result if result.index(':').nil?
+        result.gsub(':#{token.first}', self.class.escape_path(token.last))
       end
     end
 
     # Returns a sanitized String URL
     def sanitize_url(in_url)
-      url = in_url
+      url = in_url \
         # Remove all double slashes
-        .tr('//', '/') \
-
+        .gsub(/\/\//, '/') \
         # Remove every URL segment that consists solely of dots
         .split('/').reject{ |part| part =~ /^\.+$/ }.join('/') \
-
         # Always add a leading slash
         .gsub(/\A([^\/])/, '/\1')
 
       # Append a trailing slash to the URL if the unsanitized URL had one
-      url << "/" if in_url =~ /\/$/
+      url << "/" if in_url[-1].eql?('/')
 
       url
     end