Backport https://github.com/erlang/otp/commit/e7a1067112f47a860b6974882fdbd19e52b7c372
Index: lib/os_mon/src/cpu_sup.erl
--- lib/os_mon/src/cpu_sup.erl.orig
+++ lib/os_mon/src/cpu_sup.erl
@@ -163,6 +163,7 @@ handle_call({?util, D, PC}, {Client, _Tag},
 	when Flavor == sunos;
 	     Flavor == linux;
 	     Flavor == freebsd;
+	     Flavor == openbsd;
 	     Flavor == darwin ->
     case measurement_server_call(State#state.server, {?util, D, PC, Client}) of
 	{error, Reason} -> 
