diff --git a/lib/pry/cli.rb b/lib/pry/cli.rb
index c27bc154..55f77d4a 100644
--- a/lib/pry/cli.rb
+++ b/lib/pry/cli.rb
@@ -114,7 +114,7 @@ Copyright (c) 2013 John Mair (banisterfiend)
 --
 }
   on :e, :exec=, "A line of code to execute in context before the session starts" do |input|
-    exec_string << input + "\n"
+    exec_string << input << "\n"
   end
 
   on "no-pager", "Disable pager for long output" do
@@ -155,7 +155,7 @@ Copyright (c) 2013 John Mair (banisterfiend)
     puts "Installed Plugins:"
     puts "--"
     Pry.locate_plugins.each do |plugin|
-      puts "#{plugin.name}".ljust(18) + plugin.spec.summary
+      puts "#{plugin.name}".ljust(18) << plugin.spec.summary
     end
     exit
   end
diff --git a/lib/pry/code.rb b/lib/pry/code.rb
index d7eedb5b..5655d394 100644
--- a/lib/pry/code.rb
+++ b/lib/pry/code.rb
@@ -356,7 +356,7 @@ class Pry
     #
     # @return [String]
     def raw
-      @lines.map(&:line).join("\n") + "\n"
+      @lines.map(&:line).join("\n") << "\n"
     end
 
     # Return the number of lines stored.
diff --git a/lib/pry/command.rb b/lib/pry/command.rb
index 81f4eb26..4b3cb9de 100644
--- a/lib/pry/command.rb
+++ b/lib/pry/command.rb
@@ -307,8 +307,7 @@ class Pry
       collision_type ||= 'local-variable' if arg_string.match(%r{\A\s*[-+*/%&|^]*=})
 
       if collision_type
-        output.puts "#{text.bold('WARNING:')} Calling Pry command '#{command_match}'," +
-                                                          "which conflicts with a #{collision_type}.\n\n"
+        output.puts "#{text.bold('WARNING:')} Calling Pry command '#{command_match}', which conflicts with a #{collision_type}.\n\n"
       end
     rescue Pry::RescuableException
     end
diff --git a/lib/pry/command_set.rb b/lib/pry/command_set.rb
index b1d1e199..ce0d63b5 100644
--- a/lib/pry/command_set.rb
+++ b/lib/pry/command_set.rb
@@ -410,7 +410,7 @@ class Pry
       else
         commands.keys.select do |key|
           String === key && key.start_with?(search)
-        end.map{ |key| key + " " } + Bond::DefaultMission.completions
+        end.map{ |key| key + " " } << Bond::DefaultMission.completions
       end
     end
   end
diff --git a/lib/pry/commands.rb b/lib/pry/commands.rb
index 2472d02c..4b85ada1 100644
--- a/lib/pry/commands.rb
+++ b/lib/pry/commands.rb
@@ -1,6 +1,6 @@
 # Default commands used by Pry.
 Pry::Commands = Pry::CommandSet.new
 
-Dir[File.expand_path('../commands', __FILE__) + '/*.rb'].each do |file|
+Dir[File.expand_path('../commands', __FILE__) << '/*.rb'].each do |file|
   require file
 end
diff --git a/lib/pry/commands/amend_line.rb b/lib/pry/commands/amend_line.rb
index cb4ef415..838d5c85 100644
--- a/lib/pry/commands/amend_line.rb
+++ b/lib/pry/commands/amend_line.rb
@@ -48,11 +48,11 @@ class Pry
 
     def insert_into_array(array, range)
       insert_slot = Array(range).first
-      array.insert(insert_slot, arg_string[1..-1] + "\n")
+      array.insert(insert_slot, arg_string[1..-1] << "\n")
     end
 
     def replace_in_array(array, range)
-      array[range] = arg_string + "\n"
+      array[range] = arg_string << "\n"
     end
 
     # @return [Fixnum] The number of lines currently in `eval_string` (the input buffer).
diff --git a/lib/pry/commands/find_method.rb b/lib/pry/commands/find_method.rb
index 0bead171..3e61c351 100644
--- a/lib/pry/commands/find_method.rb
+++ b/lib/pry/commands/find_method.rb
@@ -97,7 +97,7 @@ class Pry
       output.puts text.bold(klass.name)
       grouped[klass].each do |method|
         header = method.name_with_owner
-        output.puts header + additional_info(header, method)
+        output.puts header << additional_info(header, method)
       end
     end
 
@@ -105,7 +105,7 @@ class Pry
     # if `-c` was not given
     def additional_info(header, method)
       if opts.content?
-        ": " + colorize_code(matched_method_lines(header, method))
+        ": " << colorize_code(matched_method_lines(header, method))
       else
         ""
       end
diff --git a/lib/pry/commands/help.rb b/lib/pry/commands/help.rb
index e6e4e198..d4c9473d 100644
--- a/lib/pry/commands/help.rb
+++ b/lib/pry/commands/help.rb
@@ -59,7 +59,7 @@ class Pry
     # @param [Array<Pry::Command>]] commands
     # @return [String] The generated help string.
     def help_text_for_commands(name, commands)
-      "#{text.bold(name)}\n" + commands.map do |command|
+      "#{text.bold(name)}\n" << commands.map do |command|
         "  #{command.options[:listing].to_s.ljust(18)} #{command.description}"
       end.join("\n")
     end
diff --git a/lib/pry/commands/ls.rb b/lib/pry/commands/ls.rb
index 441138d8..b4616fa3 100644
--- a/lib/pry/commands/ls.rb
+++ b/lib/pry/commands/ls.rb
@@ -34,8 +34,8 @@ class Pry
       opt.on :v, :verbose,   "Show methods and constants on all super-classes (ignores Pry.config.ls.ceiling)"
       opt.on :g, :globals,   "Show global variables, including those builtin to Ruby (in cyan)"
       opt.on :l, :locals,    "Show hash of local vars, sorted by descending size"
-      opt.on :c, :constants, "Show constants, highlighting classes (in blue), and exceptions (in purple).\n" +
-      " " * 32 +             "Constants that are pending autoload? are also shown (in yellow)"
+      opt.on :c, :constants, "Show constants, highlighting classes (in blue), and exceptions (in purple).\n" <<
+      " " * 32 <<            "Constants that are pending autoload? are also shown (in yellow)"
       opt.on :i, :ivars,     "Show instance variables (in blue) and class variables (in bright blue)"
       opt.on :G, :grep,      "Filter output by regular expression", :argument => true
 
diff --git a/lib/pry/commands/pry_backtrace.rb b/lib/pry/commands/pry_backtrace.rb
index d27a4816..bac23514 100644
--- a/lib/pry/commands/pry_backtrace.rb
+++ b/lib/pry/commands/pry_backtrace.rb
@@ -17,8 +17,8 @@ class Pry
     BANNER
 
     def process
-      stagger_output text.bold('Backtrace:') +
-        "\n--\n" + _pry_.backtrace.join("\n")
+      stagger_output text.bold('Backtrace:') <<
+        "\n--\n" << _pry_.backtrace.join("\n")
     end
   end
 
diff --git a/lib/pry/commands/show_info.rb b/lib/pry/commands/show_info.rb
index e2d65bb9..722e656d 100644
--- a/lib/pry/commands/show_info.rb
+++ b/lib/pry/commands/show_info.rb
@@ -63,7 +63,7 @@ class Pry
     end
 
     def content_and_header_for_code_object(code_object)
-      header(code_object) + content_for(code_object)
+      header(code_object) << content_for(code_object)
     end
 
     def content_and_headers_for_all_module_candidates(mod)
@@ -95,7 +95,7 @@ class Pry
       h << code_object_header(code_object, line_num)
       h << "\n#{Pry::Helpers::Text.bold('Number of lines:')} " <<
         "#{content_for(code_object).lines.count}\n\n"
-      h << Helpers::Text.bold('** Warning:') + " Cannot find code for #{@original_code_object.nonblank_name}. Showing superclass #{code_object.nonblank_name} instead. **\n\n" if @used_super
+      h << Helpers::Text.bold('** Warning:') << " Cannot find code for #{@original_code_object.nonblank_name}. Showing superclass #{code_object.nonblank_name} instead. **\n\n" if @used_super
       h
     end
 
@@ -128,7 +128,7 @@ class Pry
       h << " #{text.bold('name:')} #{code_object.nonblank_name}"
 
       if code_object.number_of_candidates > 1
-        h << (text.bold("\nNumber of monkeypatches: ") + code_object.number_of_candidates.to_s)
+        h << (text.bold("\nNumber of monkeypatches: ") << code_object.number_of_candidates.to_s)
         h << ". Use the `-a` option to display all available monkeypatches"
       end
       h
diff --git a/lib/pry/commands/whereami.rb b/lib/pry/commands/whereami.rb
index 134472bc..2ec82252 100644
--- a/lib/pry/commands/whereami.rb
+++ b/lib/pry/commands/whereami.rb
@@ -88,8 +88,8 @@ class Pry
 
       set_file_and_dir_locals(@file)
 
-      out = "\n#{text.bold('From:')} #{location}:\n\n" +
-        code.with_line_numbers(use_line_numbers?).with_marker(marker).to_s + "\n"
+      out = "\n#{text.bold('From:')} #{location}:\n\n" <<
+        code.with_line_numbers(use_line_numbers?).with_marker(marker).to_s << "\n"
 
       stagger_output(out)
     end
diff --git a/lib/pry/completion.rb b/lib/pry/completion.rb
index 03e5e74d..42fd8c5c 100644
--- a/lib/pry/completion.rb
+++ b/lib/pry/completion.rb
@@ -112,7 +112,7 @@ class Pry
           # Symbol
           if Symbol.respond_to?(:all_symbols)
             sym        = Regexp.quote($1)
-            candidates = Symbol.all_symbols.collect{|s| ":" + s.id2name}
+            candidates = Symbol.all_symbols.collect{|s| ":" << s.id2name}
 
             candidates.grep(/^#{sym}/)
           else
@@ -123,7 +123,7 @@ class Pry
           # Absolute Constant or class methods
           receiver = $1
           candidates = Object.constants.collect(&:to_s)
-          candidates.grep(/^#{receiver}/).collect{|e| "::" + e}
+          candidates.grep(/^#{receiver}/).collect{|e| "::" << e}
 
 
         # Complete target symbols
@@ -151,7 +151,7 @@ class Pry
           rescue RescuableException
             candidates = []
           end
-          candidates.grep(/^#{message}/).collect{|e| receiver + "::" + e}
+          candidates.grep(/^#{message}/).collect{|e| receiver << "::" << e}
 
         when /^(:[^:.]+)\.([^.]*)$/
           # Symbol
@@ -261,10 +261,10 @@ class Pry
       candidates.grep(/^#{message}/).collect { |e|
         case e
         when /^[a-zA-Z_]/
-          path.call(receiver + "." + e)
+          path.call(receiver + "." << e)
         when /^[0-9]/
         when *Operators
-          #receiver + " " + e
+          #receiver + " " << e
         end
       }.compact
     end
diff --git a/lib/pry/indent.rb b/lib/pry/indent.rb
index e760655c..848454a4 100644
--- a/lib/pry/indent.rb
+++ b/lib/pry/indent.rb
@@ -94,8 +94,8 @@ class Pry
       indent = new
       lines = str.split("\n")
       n = line_number - 1
-      to_indent = lines[0...n] + (lines[n] || "").split("def").first(1)
-      indent.indent(to_indent.join("\n") + "\n")
+      to_indent = lines[0...n] << (lines[n] || "").split("def").first(1)
+      indent.indent(to_indent.join("\n") << "\n")
       indent.module_nesting
     end
 
@@ -156,7 +156,7 @@ class Pry
         before.times{ prefix.sub! SPACES, '' }
         new_prefix = prefix + SPACES * after
 
-        line = prefix + line.lstrip unless previously_in_string
+        line = prefix << line.lstrip unless previously_in_string
 
         output += line
 
@@ -384,7 +384,7 @@ class Pry
     # @return [String]
     def correct_indentation(prompt, code, overhang=0)
       prompt = prompt.delete("\001\002")
-      line_to_measure = Pry::Helpers::Text.strip_color(prompt) + code
+      line_to_measure = Pry::Helpers::Text.strip_color(prompt) << code
       whitespace = ' ' * overhang
 
       _, cols = Terminal.screen_size