--- a/CRC32Stream.st	Sat Mar 23 21:54:24 2019 +0100
+++ b/CRC32Stream.st	Sat Mar 23 22:16:40 2019 +0100
@@ -370,8 +370,6 @@
 #if defined(HAS_CRC)
 # if defined(__x86__) || defined(__x86_64__)
 #  if defined(__clang__) || defined(__GNUC__)
-    extern unsigned char __cpu_hasSSE4_2;
-
     RETURN (__cpu_hasSSE4_2 ? true : false);
 #  endif
 # endif