diff --git a/var/spack/repos/builtin/packages/openmolcas/CMakeLists.txt.patch b/var/spack/repos/builtin/packages/openmolcas/CMakeLists.txt.patch
new file mode 100644
index 0000000000000000000000000000000000000000..61da9e046dfe14a9a07617bd4d58b140bcfa3f82
--- /dev/null
+++ b/var/spack/repos/builtin/packages/openmolcas/CMakeLists.txt.patch
@@ -0,0 +1,12 @@
+--- spack-src/CMakeLists.txt.bak	2019-11-12 20:59:54.000000000 +0900
++++ spack-src/CMakeLists.txt	2020-08-07 16:37:11.600570176 +0900
+@@ -559,7 +559,8 @@
+         if ((${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86") OR
+             (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "i686"))
+                 set (PLATFORM "LINUX")
+-        elseif (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86_64")
++	elseif ((${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86_64") OR
++                (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "aarch64"))
+                 set (PLATFORM "LINUX64")
+         elseif (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "ia64")
+                 set (PLATFORM "LINUX64_IA")
diff --git a/var/spack/repos/builtin/packages/openmolcas/package.py b/var/spack/repos/builtin/packages/openmolcas/package.py
index d8c8b0fe84672cb9698292eda3e10323c95c4f8b..c8a6e2aaa06e9cd2880945133ada1b60d8e619a6 100644
--- a/var/spack/repos/builtin/packages/openmolcas/package.py
+++ b/var/spack/repos/builtin/packages/openmolcas/package.py
@@ -23,6 +23,8 @@ class Openmolcas(CMakePackage):
     depends_on('py-pyparsing', type=('build', 'run'))
     depends_on('py-six', type=('build', 'run'))
 
+    patch('CMakeLists.txt.patch', when='target=aarch64:')
+
     def setup_build_environment(self, env):
         env.set('MOLCAS', self.prefix)