Index: libphobos/src/std/system.d
--- libphobos/src/std/system.d.orig
+++ libphobos/src/std/system.d
@@ -35,6 +35,7 @@ immutable
         watchOS,   /// watchOS
         freeBSD,   /// FreeBSD
         netBSD,    /// NetBSD
+        openBSD,    /// OpenBSD
         dragonFlyBSD, /// DragonFlyBSD
         solaris,   /// Solaris
         android,   /// Android
@@ -52,6 +53,7 @@ immutable
     else version (watchOS) OS os = OS.watchOS;
     else version (FreeBSD) OS os = OS.freeBSD;
     else version (NetBSD)  OS os = OS.netBSD;
+    else version (OpenBSD)  OS os = OS.openBSD;
     else version (DragonFlyBSD) OS os = OS.dragonFlyBSD;
     else version (Posix)   OS os = OS.otherPosix;
     else static assert(0, "Unknown OS.");
