diff --git a/rubygem-activesupport-5.1.7-Fix-FileStoreTest-test_filename_max_size-fails.patch b/rubygem-activesupport-5.1.7-Fix-FileStoreTest-test_filename_max_size-fails.patch
new file mode 100644
index 0000000..55c4b74
--- /dev/null
+++ b/rubygem-activesupport-5.1.7-Fix-FileStoreTest-test_filename_max_size-fails.patch
@@ -0,0 +1,26 @@
+From ca4be4b7788c90d94beb1e835b7019f809148d08 Mon Sep 17 00:00:00 2001
+From: Andrew White <andrew.white@unboxed.co>
+Date: Mon, 2 Apr 2018 09:34:53 +0100
+Subject: [PATCH] Backport fix for Dir::Tmpname.create from #32386
+
+The removal of path separators from the tmpname value affects all four
+supported versions of Ruby - 2.2.10, 2.3.7, 2.4.4, and 2.5.1.
+---
+ activesupport/test/caching_test.rb | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/activesupport/test/caching_test.rb b/activesupport/test/caching_test.rb
+index c67ffe69b80a..c138f10c13a5 100644
+--- a/activesupport/test/caching_test.rb
++++ b/activesupport/test/caching_test.rb
+@@ -854,7 +854,9 @@ def test_key_transformation_with_pathname
+   def test_filename_max_size
+     key = "#{'A' * ActiveSupport::Cache::FileStore::FILENAME_MAX_SIZE}"
+     path = @cache.send(:normalize_key, key, {})
+-    Dir::Tmpname.create(path) do |tmpname, n, opts|
++    basename = File.basename(path)
++    dirname = File.dirname(path)
++    Dir::Tmpname.create(basename, Dir.tmpdir + dirname) do |tmpname, n, opts|
+       assert File.basename(tmpname + ".lock").length <= 255, "Temp filename too long: #{File.basename(tmpname + '.lock').length}"
+     end
+   end
diff --git a/rubygem-activesupport.spec b/rubygem-activesupport.spec
index 4786c9f..c872fe5 100644
--- a/rubygem-activesupport.spec
+++ b/rubygem-activesupport.spec
@@ -3,7 +3,7 @@
 Name: rubygem-%{gem_name}
 Epoch: 1
 Version: 5.1.5
-Release: 2%{?dist}
+Release: 3%{?dist}
 Summary: A support libraries and Ruby core extensions extracted from the Rails framework
 Group: Development/Languages
 License: MIT
@@ -17,6 +17,10 @@ Source0: https://rubygems.org/gems/%{gem_name}-%{version}.gem
 # git checkout v5.1.5 && tar czvf activesupport-5.1.5-tests.tgz test/
 Source1: %{gem_name}-%{version}-tests.tgz
 
+# Fix test suite issue caused by change fix of CVE-2018-6914 in Ruby.
+# https://github.com/rails/rails/commit/ca4be4b7788c90d94beb1e835b7019f809148d08
+Patch1: rubygem-activesupport-5.1.7-Fix-FileStoreTest-test_filename_max_size-fails.patch
+
 # ruby package has just soft dependency on rubygem({bigdecimal,json}), while
 # ActiveSupport always requires them.
 Requires: rubygem(bigdecimal)
@@ -75,6 +79,8 @@ pushd .%{gem_instdir}
 # Move the tests into place
 tar xzvf %{SOURCE1}
 
+cat %{PATCH1} | patch -p2
+
 # These tests are really unstable, but they seems to be passing upstream :/
 for f in test/evented_file_update_checker_test.rb; do
   mv $f{,.disable}
@@ -103,6 +109,9 @@ popd
 %doc %{gem_instdir}/README.rdoc
 
 %changelog
+* Mon Apr 16 2018 Vít Ondruch <vondruch@redhat.com> - 1:5.1.5-3
+- Fix test suite issue caused by change fix of CVE-2018-6914 in Ruby.
+
 * Wed Feb 21 2018 Pavel Valena <pvalena@redhat.com> - 1:5.1.5-2
 - Allow rubygem-i18n ~> 1.0
   https://github.com/rails/rails/pull/31991