diff --git a/matlab/backward/backward_model_irf.m b/matlab/backward/backward_model_irf.m
index 39f8ac551bfd3f34ec52ef39eb610728ad5d2afb..81a3a5c9608a5ee27be192e243983a86f7c14bae 100644
--- a/matlab/backward/backward_model_irf.m
+++ b/matlab/backward/backward_model_irf.m
@@ -157,7 +157,7 @@ for i=1:length(listofshocks)
         timid = shock.dates(1)-initialconditionperiod;
         for j=1:shock.vobs
             k = find(strcmp(shock.name{i}, exonames));
-            innovations(timid,:) = innovations(timid,:) + shock.data(1,j);
+            innovations(timid,k) = innovations(timid,k) + shock.data(1,j);
         end
     else
         j = find(strcmp(listofshocks{i}, exonames));