diff --git a/devel/libfilezilla/Portfile b/devel/libfilezilla/Portfile
index 4c3a627172c67..a4f81d4696999 100644
--- a/devel/libfilezilla/Portfile
+++ b/devel/libfilezilla/Portfile
@@ -29,6 +29,9 @@ depends_build       port:pkgconfig \
 
 use_bzip2           yes
 
+# libfilezilla uses thread_local, which is not supported in Xcode < 8
+compiler.blacklist-append {clang < 800}
+
 test.run            yes
 test.dir            ${worksrcpath}/tests
 test.cmd            ./test