diff --git a/osmodel.mak b/osmodel.mak
index d0f160ae374..dd94b4098bc 100644
--- a/osmodel.mak
+++ b/osmodel.mak
@@ -1,5 +1,15 @@
-# This Makefile snippet detects the OS and the architecture MODEL
-# Keep this file in sync between druntime, phobos, and dmd repositories!
+#   osmodel.mak
+#
+# Detects and sets the macros:
+#
+#   OS         = one of {osx,linux,freebsd,openbsd,netbsd,solaris}
+#   MODEL      = one of { 32, 64 }
+#   MODEL_FLAG = one of { -m32, -m64 }
+#
+# Note:
+#   Keep this file in sync between druntime, phobos, and dmd repositories!
+# Source: https://github.com/dlang/phobos/blob/master/osmodel.mak
+
 
 ifeq (,$(OS))
   uname_S:=$(shell uname -s)
@@ -12,12 +22,12 @@ ifeq (,$(OS))
   ifeq (FreeBSD,$(uname_S))
     OS:=freebsd
   endif
-  ifeq (NetBSD,$(uname_S))
-    OS:=netbsd
-  endif
   ifeq (OpenBSD,$(uname_S))
     OS:=openbsd
   endif
+  ifeq (NetBSD,$(uname_S))
+    OS:=netbsd
+  endif
   ifeq (Solaris,$(uname_S))
     OS:=solaris
   endif