The FreeBSD declaration of timezone conflicts with Posix. diff -ur icu-49.1.orig/source/common/putilimp.h icu-49.1/source/common/putilimp.h --- icu-49.1.orig/source/common/putilimp.h 2012-03-21 18:35:16.000000000 +0100 +++ icu-49.1/source/common/putilimp.h 2012-04-24 11:38:09.000000000 +0200 @@ -116,6 +116,8 @@ # define U_TIMEZONE __timezone #elif U_PLATFORM_USES_ONLY_WIN32_API # define U_TIMEZONE _timezone +#elif U_PLATFORM == U_PF_BSD && !defined(__FreeBSD_kernel__) + /* not defined */ #elif U_PLATFORM == U_PF_OS400 /* not defined */ #else