diff --git a/matlab/set_state_space.m b/matlab/set_state_space.m
index 02705a893324e17a22a8ffc5da45e72f6b4c915d..99a919f19d937d89a4eb7219d6e7ac63f67ad1bc 100644
--- a/matlab/set_state_space.m
+++ b/matlab/set_state_space.m
@@ -110,7 +110,7 @@ dr.kae = kae;
 dr.nboth = nboth;
 dr.nfwrd = nfwrd;
 % number of forward variables in the state vector
-dr.nsfwrd = nfwrd;
+dr.nsfwrd = nfwrd+nboth;
 % number of predetermined variables in the state vector
 dr.nspred = npred+nboth;