diff --git a/matlab/histvalf.m b/matlab/histvalf.m
index 576f5ff635150a793e3b1f5081955a23e882665a..e2c1445546ada6e61da5bc30228638b74216a0c0 100644
--- a/matlab/histvalf.m
+++ b/matlab/histvalf.m
@@ -17,7 +17,7 @@ function histvalf(fname)
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
-global M_ oo_
+global M_ oo_ ex0_
 
 if ~exist(fname)
     error(['Can''t find datafile: ' fname ]);