--- third_party/zlib/BUILD.gn.orig	2020-11-09 14:36:38 UTC
+++ third_party/zlib/BUILD.gn
@@ -88,6 +88,8 @@ if (use_arm_neon_optimizations) {
       defines = [ "CRC32_ARMV8_CRC32" ]
       if (is_android) {
         defines += [ "ARMV8_OS_ANDROID" ]
+      } else if (is_bsd) {
+        defines += [ "ARMV8_OS_FREEBSD" ]
       } else if (is_linux || is_chromeos) {
         defines += [ "ARMV8_OS_LINUX" ]
       } else if (is_mac) {