diff --git a/.gitignore b/.gitignore
index 3144db2..8fb891c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,5 @@
 /concurrent-ruby-1.0.2.gem
 /concurrent-ruby-1.0.4-specs.tar.gz
 /concurrent-ruby-1.0.4.gem
+/concurrent-ruby-1.0.5-specs.tar.gz
+/concurrent-ruby-1.0.5.gem
diff --git a/concurrent-ruby-1.0.5-fix-inspect-output.patch b/concurrent-ruby-1.0.5-fix-inspect-output.patch
new file mode 100644
index 0000000..b8e1b84
--- /dev/null
+++ b/concurrent-ruby-1.0.5-fix-inspect-output.patch
@@ -0,0 +1,18 @@
+diff --git a/lib/concurrent/map.rb b/lib/concurrent/map.rb
+index f3aa55d5..34696efc 100644
+--- a/lib/concurrent/map.rb
++++ b/lib/concurrent/map.rb
+@@ -210,12 +210,8 @@ module Concurrent
+     undef :freeze
+ 
+     # @!visibility private
+-    DEFAULT_OBJ_ID_STR_WIDTH = 0.size == 4 ? 7 : 14 # we want to look "native", 7 for 32-bit, 14 for 64-bit
+-    # override default #inspect() method: firstly, we don't want to be spilling our guts (i-vars), secondly, MRI backend's
+-    # #inspect() call on its @backend i-var will bump @backend's iter level while possibly yielding GVL
+     def inspect
+-      id_str = (object_id << 1).to_s(16).rjust(DEFAULT_OBJ_ID_STR_WIDTH, '0')
+-      "#<#{self.class.name}:0x#{id_str} entries=#{size} default_proc=#{@default_proc.inspect}>"
++      format '%s entries=%d default_proc=%s>', to_s[0..-2], size.to_s, @default_proc.inspect
+     end
+ 
+     private
diff --git a/rubygem-concurrent-ruby.spec b/rubygem-concurrent-ruby.spec
index d0ecd71..a1683ce 100644
--- a/rubygem-concurrent-ruby.spec
+++ b/rubygem-concurrent-ruby.spec
@@ -2,16 +2,19 @@
 %global gem_name concurrent-ruby
 
 Name: rubygem-%{gem_name}
-Version: 1.0.4
-Release: 2%{?dist}
+Version: 1.0.5
+Release: 1%{?dist}
 Summary: Modern concurrency tools for Ruby
 Group: Development/Languages
 License: MIT
 URL: http://www.concurrent-ruby.com
 Source0: https://rubygems.org/gems/%{gem_name}-%{version}.gem
 # git clone https://github.com/ruby-concurrency/concurrent-ruby.git && cd concurrent-ruby
-# git checkout v1.0.4 && tar czvf concurrent-ruby-1.0.4-specs.tar.gz spec/
+# git checkout v1.0.5 && tar czvf concurrent-ruby-1.0.5-specs.tar.gz spec/
 Source1: %{gem_name}-%{version}-specs.tar.gz
+# Avoid sporadic test failures due to wrong object_id formatting.
+# https://github.com/ruby-concurrency/concurrent-ruby/pull/651
+Patch1: concurrent-ruby-1.0.5-fix-inspect-output.patch
 BuildRequires: ruby(release)
 BuildRequires: rubygems-devel
 BuildRequires: ruby >= 1.9.3
@@ -43,6 +46,8 @@ gem unpack %{SOURCE0}
 
 gem spec %{SOURCE0} -l --ruby > %{gem_name}.gemspec
 
+%patch1 -p1
+
 %build
 # Create the gem as gem install only works on a gem file
 gem build %{gem_name}.gemspec
@@ -89,6 +94,9 @@ popd
 %doc %{gem_instdir}/README.md
 
 %changelog
+* Tue May 09 2017 Vít Ondruch <vondruch@redhat.com> - 1.0.5-1
+- Update to Concurrent Ruby 1.0.5.
+
 * Sat Feb 11 2017 Fedora Release Engineering <releng@fedoraproject.org> - 1.0.4-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_26_Mass_Rebuild
 
diff --git a/sources b/sources
index 9112eaf..3dbf1ad 100644
--- a/sources
+++ b/sources
@@ -1,2 +1,2 @@
-SHA512 (concurrent-ruby-1.0.4-specs.tar.gz) = ecdd08b1e30f60fe9b7cf3973ca74669cc978c23c698d16c75538e13afb41240c87ac6ab3725ffd797fe9786c9fb642704ac052042defa89f764a15abbd864a2
-SHA512 (concurrent-ruby-1.0.4.gem) = 84ab0ba23822012dbdf35165ea80080bc995c393eb734672b45e076a278324acad60e07160b3a549699e19d35af6ac8b21d19817e57e60bb53c1ee94401221cb
+SHA512 (concurrent-ruby-1.0.5-specs.tar.gz) = f13da35b9b6cce1182d822723811b27aa661c3dfd231e2d3ace09451ee01f737d343d1d18f5debc296b1534ef0b6a919e679a8ef693a7d75b557e65d19432ef0
+SHA512 (concurrent-ruby-1.0.5.gem) = 523df60096e77a377405b71f9133f28284ca73284bb52456bf1e1a38dbb34c593b3aa2ed9ceb019afbed4805ba2bc3d7c846d3a66139924ec7fa0ccb3fcf9324