diff --git a/rubygen-ferret-posh.h-aarch64.patch b/rubygem-ferret-posh.h-aarch64.patch
similarity index 100%
rename from rubygen-ferret-posh.h-aarch64.patch
rename to rubygem-ferret-posh.h-aarch64.patch
diff --git a/rubygem-ferret-posh.h-s390x.patch b/rubygem-ferret-posh.h-s390x.patch
new file mode 100644
index 0000000..f21e435
--- /dev/null
+++ b/rubygem-ferret-posh.h-s390x.patch
@@ -0,0 +1,14 @@
+--- ferret-0.11.8.4/ext/posh.h.s390x	2018-01-04 17:41:28.554656256 +0900
++++ ferret-0.11.8.4/ext/posh.h	2018-01-04 17:47:46.769599536 +0900
+@@ -519,6 +519,11 @@
+ #  endif
+ #endif
+ 
++#if defined __s390__
++# define POSH_CPU_S390 1
++# define POSH_CPU_STRING "S/390"
++#endif
++
+ #if !defined POSH_CPU_STRING
+ #  error POSH cannot determine target CPU
+ #  define POSH_CPU_STRING "Unknown" /* this is here for Doxygen's benefit */
diff --git a/rubygem-ferret.spec b/rubygem-ferret.spec
index 34c0a47..ceb6ac9 100644
--- a/rubygem-ferret.spec
+++ b/rubygem-ferret.spec
@@ -3,7 +3,7 @@
 Summary: Full-featured text search engine library
 Name: rubygem-%{gem_name}
 Version: 0.11.8.4
-Release: 18%{?dist}
+Release: 19%{?dist}
 Group: Development/Languages
 # License from
 # - MIT-LICENSE: MIT
@@ -21,7 +21,10 @@ Patch2: rubygem-ferret-0.11.8.4-Block-variables-has-local-scopes.patch
 # See https://bugs.ruby-lang.org/issues/9889
 Patch3: rubygem-ferret-0.11.8.4-ruby22-hashsize.patch
 # fix build on aarch64
-Patch4: rubygen-ferret-posh.h-aarch64.patch
+Patch4: rubygem-ferret-posh.h-aarch64.patch
+# s390x build
+# from http://pkg-ruby-extras-maintainers.alioth.debian.narkive.com/fQZGgAAD/dre-maint-rc-bug-474724
+Patch5: rubygem-ferret-posh.h-s390x.patch
 BuildRequires: rubygems-devel
 BuildRequires: ruby-devel
 BuildRequires: rubygem(minitest) < 5
@@ -50,6 +53,7 @@ gem unpack %{SOURCE0}
 %patch2 -p2
 %patch3 -p1
 %patch4 -p1
+%patch5 -p1
 
 gem spec %{SOURCE0} -l --ruby > %{gem_name}.gemspec
 
@@ -116,6 +120,10 @@ popd
 %{gem_instdir}/test/
 
 %changelog
+* Thu Jan 04 2018 Mamoru TASAKA <mtasaka@fedoraproject.org> - 0.11.8.4-19
+- F-28: rebuild for ruby25
+- s390x fix for posh.h
+
 * Thu Jan 04 2018 Mamoru TASAKA <mtasaka@fedoraproject.org> - 0.11.8.4-18
 - F-28: rebuild for ruby25