2 files changed, 6 insertions, 5 deletions
diff --git a/activesupport/lib/active_support/multibyte/chars.rb b/activesupport/lib/active_support/multibyte/chars.rb
index c107aad6bb..8823e4a5ed 100644
--- a/activesupport/lib/active_support/multibyte/chars.rb
+++ b/activesupport/lib/active_support/multibyte/chars.rb
@@ -105,7 +105,7 @@ module ActiveSupport #:nodoc:
         # Example:
         #   ('Café'.mb_chars + ' périferôl').to_s #=> "Café périferôl"
         def +(other)
-          self << other
+          chars(@wrapped_string + other)
         end
 
         # Like <tt>String#=~</tt> only it returns the character offset (in codepoints) instead of the byte offset.
@@ -316,11 +316,12 @@ module ActiveSupport #:nodoc:
           result = @wrapped_string.slice(*args)
         elsif args.size == 1 && args[0].kind_of?(Numeric)
           character = Unicode.u_unpack(@wrapped_string)[args[0]]
-          result = character.nil? ? nil : [character].pack('U')
+          result = character && [character].pack('U')
         else
-          result = Unicode.u_unpack(@wrapped_string).slice(*args).pack('U*')
+          cps = Unicode.u_unpack(@wrapped_string).slice(*args)
+          result = cps && cps.pack('U*')
         end
-        result.nil? ? nil : chars(result)
+        result && chars(result)
       end
       alias_method :[], :slice
 
diff --git a/activesupport/lib/active_support/multibyte/unicode.rb b/activesupport/lib/active_support/multibyte/unicode.rb
index f91e50c755..11c72d873b 100644
--- a/activesupport/lib/active_support/multibyte/unicode.rb
+++ b/activesupport/lib/active_support/multibyte/unicode.rb
@@ -9,7 +9,7 @@ module ActiveSupport
       NORMALIZATION_FORMS = [:c, :kc, :d, :kd]
 
       # The Unicode version that is supported by the implementation
-      UNICODE_VERSION = '5.1.0'
+      UNICODE_VERSION = '5.2.0'
 
       # The default normalization used for operations that require normalization. It can be set to any of the
       # normalizations in NORMALIZATION_FORMS.