--- Modules/CMakePlatformId.h.in.orig	2021-02-24 15:08:43 UTC
+++ Modules/CMakePlatformId.h.in
@@ -17,6 +17,9 @@
 #elif defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
 # define PLATFORM_ID "Windows"
 
+#elif defined(__BSDSUniX__) || defined(__BSDSUniX)
+# define PLATFORM_ID "BSDSUniX"
+
 #elif defined(__FreeBSD__) || defined(__FreeBSD)
 # define PLATFORM_ID "FreeBSD"