diff --git a/matlab/perfect-foresight-models/make_ex_.m b/matlab/perfect-foresight-models/make_ex_.m
index 3234afbeca94783354aa58564584a122e634826e..f3a9f483fb3c0a5b6ff8a182b8112c07bc1bd38d 100644
--- a/matlab/perfect-foresight-models/make_ex_.m
+++ b/matlab/perfect-foresight-models/make_ex_.m
@@ -49,22 +49,26 @@ if isempty(oo_.initval_series)
             error('histval and endval cannot be used simultaneously')
         end
     end
-elseif M_.exo_nbr > 0
-    x = oo_.initval_series{M_.exo_names{:}}.data;
-    oo_.exo_simul = x(M_.orig_maximum_lag-M_.maximum_lag+1:M_.orig_maximum_lag + options_.periods + M_.maximum_lead,:);
-    if ~isempty(M_.exo_histval)
-        oo_.exo_simul(1:M_.maximum_lag, :) ...
-            = M_.exo_histval(:, 1:M_.maximum_lag)';
+else
+    if M_.exo_nbr > 0
+        x = oo_.initval_series{M_.exo_names{:}}.data;
+        oo_.exo_simul = x(M_.orig_maximum_lag-M_.maximum_lag+1:M_.orig_maximum_lag + options_.periods + M_.maximum_lead,:);
+        if ~isempty(M_.exo_histval)
+            oo_.exo_simul(1:M_.maximum_lag, :) ...
+                = M_.exo_histval(:, 1:M_.maximum_lag)';
+        end
+    else
+        oo_.exo_simul=zeros(M_.maximum_lag + options_.periods + M_.maximum_lead,M_.exo_nbr);
     end
-elseif M_.exo_det_nbr > 0
-    x_det = oo_.initval_series{M_.exo_det_names{:}}.data;
-    oo_.exo_det_simul = x_det(M_.orig_maximum_lag-M_.maximum_lag+1:M_.orig_maximum_lag + options_.periods + M_.maximum_lead,:);
-    if ~isempty(M_.exo_det_histval)
-        oo_.exo_det_simul(1:M_.maximum_lag, :) ...
-            = M_.exo_det_histval(:, 1:M_.maximum_lag)';
+    if M_.exo_det_nbr > 0
+        x_det = oo_.initval_series{M_.exo_det_names{:}}.data;
+        oo_.exo_det_simul = x_det(M_.orig_maximum_lag-M_.maximum_lag+1:M_.orig_maximum_lag + options_.periods + M_.maximum_lead,:);
+        if ~isempty(M_.exo_det_histval)
+            oo_.exo_det_simul(1:M_.maximum_lag, :) ...
+                = M_.exo_det_histval(:, 1:M_.maximum_lag)';
+        end
     end
 end
-
 % Initialize oo_.exo_det_simul
 if M_.exo_det_nbr > 0
     if isempty(M_.exo_det_histval)