diff --git a/devel/zix/Portfile b/devel/zix/Portfile
index 6d2beda56e4c3..a8dbc158c2a8a 100644
--- a/devel/zix/Portfile
+++ b/devel/zix/Portfile
@@ -3,8 +3,12 @@
 PortSystem          1.0
 
 PortGroup           gitlab  1.0
+PortGroup           legacysupport 1.1
 PortGroup           meson   1.0
 
+# clock_gettime
+legacysupport.newest_darwin_requires_legacy 15
+
 gitlab.setup        drobilla zix 0.4.2 v
 revision            0
 
@@ -21,3 +25,6 @@ checksums           rmd160  c69eb969044123e8fe16aaa9be1a76c2335c90a0 \
                     size    74432
 
 compiler.c_standard 1999
+# ERROR: C++ Compiler does not support -std=c++17
+compiler.cxx_standard \
+                    2017