diff --git a/CMakeLists.txt b/CMakeLists.txt
index f4f8e67..c313118 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -113,16 +113,6 @@ if(NOT MSVC)
   if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
     target_link_libraries(snmalloc_lib INTERFACE atomic)
   endif()
-  if(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86_64")
-   target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "amd64")
-   target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "AMD64")
-   target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86")
-   target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  # XXX elseif ARM?
-  endif()
 endif()
 
 if (WIN32)
@@ -138,17 +128,11 @@ if (WIN32)
   endif()
 endif()
 
-if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  if(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86_64")
-    target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "amd64")
-   target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "AMD64")
-   target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86")
-   target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
-  endif()
-endif ()
+# detect support for cmpxchg16b; werror is needed to make sure mcx16 must be used by targets
+check_cxx_compiler_flag("-Werror -Wextra -Wall -mcx16" SNMALLOC_COMPILER_SUPPORT_MCX16)
+if(SNMALLOC_COMPILER_SUPPORT_MCX16)
+  target_compile_options(snmalloc_lib INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-mcx16>)
+endif()
 
 if(USE_SNMALLOC_STATS)
   target_compile_definitions(snmalloc_lib INTERFACE -DUSE_SNMALLOC_STATS)
diff --git a/src/mem/entropy.h b/src/mem/entropy.h
index d9b40ae..cf5f179 100644
--- a/src/mem/entropy.h
+++ b/src/mem/entropy.h
@@ -4,8 +4,10 @@
 #include "../pal/pal.h"
 
 #include <cstdint>
-#include <random>
 #include <type_traits>
+#ifndef SNMALLOC_PLATFORM_HAS_GETENTROPY
+#  include <random>
+#endif
 
 namespace snmalloc
 {
@@ -18,9 +20,13 @@ namespace snmalloc
   template<typename PAL>
   std::enable_if_t<!pal_supports<Entropy, PAL>, uint64_t> get_entropy64()
   {
+#ifdef SNMALLOC_PLATFORM_HAS_GETENTROPY
+    return DefaultPal::get_entropy64();
+#else
     std::random_device rd;
     uint64_t a = rd();
     return (a << 32) ^ rd();
+#endif
   }
 
   class LocalEntropy
@@ -139,4 +145,4 @@ namespace snmalloc
       return result;
     }
   };
-} // namespace snmalloc
\ No newline at end of file
+} // namespace snmalloc