diff --git a/CMakeLists.txt b/CMakeLists.txt
index bf434b691d..54cc320b3e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,14 +34,6 @@ find_package(LibXml2 REQUIRED)
 include(SwiftSupport)
 include(GNUInstallDirs)
 
-if(CMAKE_SYSTEM_NAME STREQUAL Linux)
-  include(CheckSymbolExists)
-  include(CheckIncludeFile)
-  list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
-  check_include_file("sched.h" HAVE_SCHED_H)
-  check_symbol_exists(sched_getaffinity "sched.h" HAVE_SCHED_GETAFFINITY)
-endif()
-
 string(TOLOWER ${CMAKE_SYSTEM_NAME} swift_os)
 get_swift_host_arch(swift_arch)
 
diff --git a/CoreFoundation/CMakeLists.txt b/CoreFoundation/CMakeLists.txt
index fc1b5f9f71..e2fb89a10a 100644
--- a/CoreFoundation/CMakeLists.txt
+++ b/CoreFoundation/CMakeLists.txt
@@ -368,6 +368,17 @@ if(CMAKE_SYSTEM_NAME STREQUAL Linux OR CMAKE_SYSTEM_NAME STREQUAL Android)
   target_compile_definitions(CFXMLInterface
                              PRIVATE
                                -D_GNU_SOURCE)
+
+  if(CMAKE_SYSTEM_NAME STREQUAL Linux)
+    include(CheckSymbolExists)
+    include(CheckIncludeFile)
+    list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
+    check_include_file("sched.h" HAVE_SCHED_H)
+    if(HAVE_SCHED_H)
+      check_symbol_exists(sched_getaffinity "sched.h" HAVE_SCHED_GETAFFINITY)
+    endif()
+  endif()
+
   if(HAVE_SCHED_GETAFFINITY)
     target_compile_definitions(CoreFoundation
                                PRIVATE