diff --git a/matlab/get_companion_matrix.m b/matlab/get_companion_matrix.m
index 35a17020d..7450c4fc4 100644
--- a/matlab/get_companion_matrix.m
+++ b/matlab/get_companion_matrix.m
@@ -90,18 +90,27 @@ else
         q = length(M_.var.(var_model_name).eqn)-m;
         ecm_eqnums = zeros(m, 1);
         ecm_eqnums_in_auxiliary_model = zeros(m, 1);
-        for i=1:m
-            number = get_equation_number_by_tag(M_.pac.(pac_model_name).undiff_eqtags{i});
-            if number>0
-                ecm_eqnums(i) = number;
-                ide = find(M_.var.(var_model_name).eqn==number);
-                if isempty(ide)
-                    error('(eq = %s, eq_in_aux_model = %s) This is most likely a bug. Please contact the DynareTeam.', int2str(number), int2str(ide))
-                else
-                    ecm_eqnums_in_auxiliary_model(i) = ide;
-                end
+        trend_eqnums = zeros(q, 1);
+        trend_eqnums_in_auxiliary_model = zeros(q, 1);
+        % EC equations in the order of M_.pac.(pac_model_name).undiff_eqtags{i}
+        ecm = zeros(m, 1);
+        for i = 1:m
+            ecm(i) = get_equation_number_by_tag(M_.pac.(pac_model_name).undiff_eqtags{i});
+        end
+        % Trend equations
+        trends = setdiff(M_.var.(var_model_name).eqn(:), ecm);
+        i1 = 1;
+        i2 = 1;
+        for i=1:m+q
+            % Only EC or trend equations are allowed in this model.
+            if ismember(M_.var.(var_model_name).eqn(i), ecm)
+                ecm_eqnums(i1) = M_.var.(var_model_name).eqn(i);
+                ecm_eqnums_in_auxiliary_model(i1) = i;
+                i1 = i1 + 1;
             else
-                error('%s is not declared as an equation in the model block!', M_.pac.(pac_model_name).undiff_eqtag{i})
+                trend_eqnums(i2) = M_.var.(var_model_name).eqn(i);
+                trend_eqnums_in_auxiliary_model(i2) = i;
+                i2 = i2 + 1;
             end
         end
         % Check that the lhs of candidate ecm equations are at least first differences.
@@ -112,20 +121,9 @@ else
         if any(~difference_orders_in_error_correction_eq)
             error('Model %s is not a VECM model! LHS variables should be in difference', var_model_name)
         end
-        % Get the indices of the trend equations.
-        trend_eqnums = transpose(setdiff(M_.var.(var_model_name).eqn,ecm_eqnums));
-        trend_eqnums_in_auxiliary_model = zeros(q, 1);
-        for i=1:q
-            idt = find(M_.var.(var_model_name).eqn==trend_eqnums(i));
-            if isempty(idt)
-                error('(eq = %s, eq_in_aux_model = %s) This is most likely a bug. Please contact the DynareTeam.', int2str(trend_eqnums(i)), int2str(idt))
-            else
-                trend_eqnums_in_auxiliary_model(i) = idt;
-            end
-        end
         % Get the trend variables indices (lhs variables in trend equations).
         [~, id_trend_in_var, ~] = intersect(M_.var.(var_model_name).eqn, trend_eqnums);
-        trend_variables = M_.var.(var_model_name).lhs(id_trend_in_var);
+        trend_variables = reshape(M_.var.(var_model_name).lhs(id_trend_in_var), q, 1);
         % Get the rhs variables in trend equations.
         trend_autoregressive_variables = zeros(q, 1);
         for i=1:q