diff --git a/lib/jekyll/regenerator.rb b/lib/jekyll/regenerator.rb
index 2d84ee34..c7d47c59 100644
--- a/lib/jekyll/regenerator.rb
+++ b/lib/jekyll/regenerator.rb
@@ -76,7 +76,7 @@ module Jekyll
     #
     # returns a boolean
     def source_modified_or_dest_missing?(source_path, dest_path)
-      modified?(source_path) || (dest_path and !File.exist?(dest_path))
+      modified?(source_path) || (dest_path && !File.exist?(dest_path))
     end
 
     # Checks if a path's (or one of its dependencies)
diff --git a/lib/jekyll/static_file.rb b/lib/jekyll/static_file.rb
index 6f24f7d2..efa836d1 100644
--- a/lib/jekyll/static_file.rb
+++ b/lib/jekyll/static_file.rb
@@ -75,7 +75,7 @@ module Jekyll
     def write(dest)
       dest_path = destination(dest)
 
-      return false if File.exist?(dest_path) and !modified?
+      return false if File.exist?(dest_path) && !modified?
       @@mtimes[path] = mtime
 
       FileUtils.mkdir_p(File.dirname(dest_path))
diff --git a/lib/jekyll/stevenson.rb b/lib/jekyll/stevenson.rb
index 9a9f412e..ea26c8b5 100644
--- a/lib/jekyll/stevenson.rb
+++ b/lib/jekyll/stevenson.rb
@@ -14,7 +14,7 @@ module Jekyll
       severity ||= UNKNOWN
       @logdev = set_logdevice(severity)
 
-      if @logdev.nil? or severity < @level
+      if @logdev.nil? || severity < @level
         return true
       end
       progname ||= @progname
diff --git a/lib/jekyll/tags/highlight.rb b/lib/jekyll/tags/highlight.rb
index 616dfdbf..13c4e8e8 100644
--- a/lib/jekyll/tags/highlight.rb
+++ b/lib/jekyll/tags/highlight.rb
@@ -27,7 +27,7 @@ module Jekyll
               @highlight_options[key.to_sym] = value || true
             end
           end
-          @highlight_options[:linenos] = "inline" if @highlight_options.key?(:linenos) and @highlight_options[:linenos] == true
+          @highlight_options[:linenos] = "inline" if @highlight_options.key?(:linenos) && @highlight_options[:linenos] == true
         else
           raise SyntaxError.new <<-eos
 Syntax Error in tag 'highlight' while parsing the following markup:
diff --git a/lib/jekyll/tags/include.rb b/lib/jekyll/tags/include.rb
index 6082a4cc..e3bee115 100644
--- a/lib/jekyll/tags/include.rb
+++ b/lib/jekyll/tags/include.rb
@@ -115,7 +115,7 @@ eos
         validate_path(path, dir, site.safe)
 
         # Add include to dependency tree
-        if context.registers[:page] and context.registers[:page].has_key? "path"
+        if context.registers[:page] && context.registers[:page].has_key?("path")
           site.regenerator.add_dependency(
             site.in_source_dir(context.registers[:page]["path"]),
             path
diff --git a/lib/jekyll/utils.rb b/lib/jekyll/utils.rb
index c0c56579..d18b41c7 100644
--- a/lib/jekyll/utils.rb
+++ b/lib/jekyll/utils.rb
@@ -31,8 +31,8 @@ module Jekyll
     # Thanks to whoever made it.
     def deep_merge_hashes!(target, overwrite)
       overwrite.each_key do |key|
-        if (overwrite[key].is_a?(Hash) or overwrite[key].is_a?(Drops::Drop)) and
-            (target[key].is_a?(Hash) or target[key].is_a?(Drops::Drop))
+        if (overwrite[key].is_a?(Hash) || overwrite[key].is_a?(Drops::Drop)) &&
+            (target[key].is_a?(Hash) || target[key].is_a?(Drops::Drop))
           target[key] = Utils.deep_merge_hashes(target[key], overwrite[key])
           next
         end