diff --git a/rubygem-ensure_valid_encoding.spec b/rubygem-ensure_valid_encoding.spec
index 9aea935..604b740 100644
--- a/rubygem-ensure_valid_encoding.spec
+++ b/rubygem-ensure_valid_encoding.spec
@@ -1,4 +1,9 @@
 %global	gem_name	ensure_valid_encoding
+%if 0%{?fedora} >= 21
+%global	gem_minitest	rubygem(minitest4)
+%else
+%global	gem_minitest	rubygem(minitest)
+%endif
 
 Name:		rubygem-%{gem_name}
 Version:	0.5.3
@@ -11,7 +16,7 @@ Source0:	https://rubygems.org/gems/%{gem_name}-%{version}.gem
 
 BuildRequires:	ruby(release)
 BuildRequires:	rubygems-devel
-BuildRequires:	rubygem(minitest)
+BuildRequires:	%gem_minitest
 Requires:	ruby(release)
 Requires:	ruby(rubygems)
 BuildArch:	noarch
@@ -56,7 +61,7 @@ popd
 
 %check
 pushd .%{gem_instdir}
-testrb -Ilib test/*_test.rb
+ruby -Ilib:. -e 'gem "minitest", "<5" ; Dir.glob("test/*_test.rb").each {|f| require f}'
 popd
 
 %files
@@ -71,8 +76,8 @@ popd
 %doc	%{gem_docdir}
 
 %changelog
-* Sun Jun 08 2014 Fedora Release Engineering <rel-eng@lists.fedoraproject.org> - 0.5.3-2
-- Rebuilt for https://fedoraproject.org/wiki/Fedora_21_Mass_Rebuild
+* Thu Jun 12 2014 Mamoru TASAKA <mtasaka@fedoraproject.org> - 0.5.3-2
+- Force to use minitest ver4 for now
 
 * Tue Nov 26 2013 TASAKA Mamoru <mtasaka@tbz.t-com.ne.jp> - 0.5.3-1
 - Initial package