diff --git a/cmake/extensions/CMakeLists.txt b/cmake/extensions/CMakeLists.txt
index 953d6b8b8..9e6184f5d 100644
--- a/cmake/extensions/CMakeLists.txt
+++ b/cmake/extensions/CMakeLists.txt
@@ -273,11 +273,11 @@ else()
 endif()
 
 set(_libffi_system_dir ${CMAKE_SYSTEM_PROCESSOR})
-if("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "i686")
+if(CMAKE_SYSTEM_PROCESSOR STREQUAL "i686")
   set(_libffi_system_dir "x86")
-elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86_64" OR "${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "amd64")
+elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64" OR CMAKE_SYSTEM_PROCESSOR STREQUAL "amd64")
   set(_libffi_system_dir "x86")
-elseif("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "arm")
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm")
   set(_libffi_system_dir "arm")
 endif()
 # Common ctypes sources