diff --git a/mk/lib.mk b/mk/lib.mk
index 3d503364f..a5a067e48 100644
--- a/mk/lib.mk
+++ b/mk/lib.mk
@@ -14,20 +14,34 @@ install-tests-groups :=
 
 ifdef HOST_OS
   HOST_KERNEL = $(firstword $(subst -, ,$(HOST_OS)))
+  ifeq ($(patsubst mingw%,,$(HOST_KERNEL)),)
+    HOST_MINGW = 1
+    HOST_WINDOWS = 1
+  endif
   ifeq ($(HOST_KERNEL), cygwin)
     HOST_CYGWIN = 1
+    HOST_WINDOWS = 1
+    HOST_UNIX = 1
   endif
   ifeq ($(patsubst darwin%,,$(HOST_KERNEL)),)
     HOST_DARWIN = 1
+    HOST_UNIX = 1
   endif
   ifeq ($(patsubst freebsd%,,$(HOST_KERNEL)),)
     HOST_FREEBSD = 1
+    HOST_UNIX = 1
+  endif
+  ifeq ($(patsubst netbsd%,,$(HOST_KERNEL)),)
+    HOST_NETBSD = 1
+    HOST_UNIX = 1
   endif
   ifeq ($(HOST_KERNEL), linux)
     HOST_LINUX = 1
+    HOST_UNIX = 1
   endif
   ifeq ($(patsubst solaris%,,$(HOST_KERNEL)),)
     HOST_SOLARIS = 1
+    HOST_UNIX = 1
   endif
 endif