diff --git a/crypto/CMakeLists.txt b/crypto/CMakeLists.txt
index 8541bbb7..1cd84589 100644
--- a/crypto/CMakeLists.txt
+++ b/crypto/CMakeLists.txt
@@ -40,7 +40,7 @@ if(NOT OPENSSL_NO_ASM)
     # CMake does not add -isysroot and -arch flags to assembly.
     if (APPLE)
       if (CMAKE_OSX_SYSROOT)
-        set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -isysroot ${CMAKE_OSX_SYSROOT}")
+        set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -isysroot \"${CMAKE_OSX_SYSROOT}\"")
       endif()
       foreach(arch ${CMAKE_OSX_ARCHITECTURES})
         set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -arch ${arch}")