diff --git a/rubygem-ferret.spec b/rubygem-ferret.spec
index 0a0370e..429dd65 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: 9%{?dist}
+Release: 10%{?dist}
 Group: Development/Languages
 # License from
 # - MIT-LICENSE: MIT
@@ -21,6 +21,8 @@ Patch1: rubygem-ferret-0.11.8.4-make-rake-just-development-dependency.patch
 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
 BuildRequires: rubygems-devel
 BuildRequires: ruby-devel
 BuildRequires: rubygem(minitest) < 5
@@ -48,6 +50,7 @@ gem unpack %{SOURCE0}
 %patch0 -p2
 %patch2 -p2
 %patch3 -p1
+%patch4 -p1
 
 gem spec %{SOURCE0} -l --ruby > %{gem_name}-%{version}.gemspec
 %patch1 -p1
@@ -111,6 +114,9 @@ popd
 %{gem_instdir}/test/
 
 %changelog
+* Mon Jan 26 2015 Marcin Juszkiewicz <mjuszkiewicz@redhat.com> - 0.11.8.4-10
+- add aarch64 definitions to posh.h to fix FTBFS
+
 * Sun Jan 18 2015 Mamoru TASAKA <mtasaka@fedoraproject.org> - 0.11.8.4-9
 - Rebuild for https://fedoraproject.org/wiki/Changes/Ruby_2.2
 - Fix RHASH_SIZE related fix failure
diff --git a/rubygen-ferret-posh.h-aarch64.patch b/rubygen-ferret-posh.h-aarch64.patch
new file mode 100644
index 0000000..ccfb893
--- /dev/null
+++ b/rubygen-ferret-posh.h-aarch64.patch
@@ -0,0 +1,18 @@
+Index: ferret-0.11.8.4/ext/posh.h
+===================================================================
+--- ferret-0.11.8.4.orig/ext/posh.h
++++ ferret-0.11.8.4/ext/posh.h
+@@ -512,6 +512,13 @@ Metrowerks:
+ #  define POSH_CPU_STRING "PA-RISC"
+ #endif
+ 
++#if defined __aarch64__ || defined __arm64__ || defined FORCE_DOXYGEN
++#  define POSH_CPU_AARCH64 /**<if defined, target CPU is AArch64 */
++#  if !defined FORCE_DOXYGEN
++#     define POSH_CPU_STRING "AArch64"
++#  endif
++#endif
++
+ #if !defined POSH_CPU_STRING
+ #  error POSH cannot determine target CPU
+ #  define POSH_CPU_STRING "Unknown" /* this is here for Doxygen's benefit */