diff --git a/matlab/graph_decomp.m b/matlab/graph_decomp.m
index 0820153163f8754eaba1b0de36c344d1cc3724e1..7b150a5da03b081880c4c297ca5e9af1a7828b47 100644
--- a/matlab/graph_decomp.m
+++ b/matlab/graph_decomp.m
@@ -52,7 +52,7 @@ fig_name_long = opts_decomp.fig_name;
 
 use_shock_groups = DynareOptions.plot_shock_decomp.use_shock_groups;
 screen_shocks = opts_decomp.screen_shocks;
-if use_shock_groups | comp_nbr<=18
+if ~isempty(use_shock_groups) || comp_nbr<=18
     screen_shocks=0;
 end
 if use_shock_groups
@@ -189,7 +189,7 @@ for j=1:nvar
         hold on
         ht = text(0.3,y1+0.3*height,labels(i,:),'Interpreter','none');
         hold on
-        if interactive && (~isoctave && use_shock_groups)
+        if interactive && (~isoctave && ~isempty(use_shock_groups))
             mydata.fig_name = DynareOptions.plot_shock_decomp.fig_name(2:end);
             mydata.use_shock_groups = DynareOptions.plot_shock_decomp.use_shock_groups;
             mydata.shock_group = shock_groups.(shock_ind{i});
diff --git a/matlab/graph_decomp_detail.m b/matlab/graph_decomp_detail.m
index 527b5f946e2d9c80bc3f6122e195195747dd6f3d..2605dbac3e3eb93494a276ac40b8811317231997 100644
--- a/matlab/graph_decomp_detail.m
+++ b/matlab/graph_decomp_detail.m
@@ -52,7 +52,7 @@ if ~isempty(opts_decomp.type)
     fig_mode = [fig_mode '_'];
 end
 screen_shocks = opts_decomp.screen_shocks;
-if DynareOptions.plot_shock_decomp.use_shock_groups | comp_nbr<=18
+if ~isempty(DynareOptions.plot_shock_decomp.use_shock_groups) || comp_nbr<=18
     screen_shocks=0;
 end
 fig_name_long = opts_decomp.fig_name;
@@ -191,7 +191,7 @@ for j=1:nvar
             a0(4)=max(a(4),a0(4));
             set(gca,'ylim',a0(3:4))
             hold on, h1=plot(x(2:end),z1(end,:),'k-','LineWidth',2);
-            if interactive && (~isoctave && use_shock_groups)
+            if interactive && (~isoctave && ~isempty(use_shock_groups))
                 mydata.fig_name = DynareOptions.plot_shock_decomp.fig_name(2:end);
                 mydata.use_shock_groups = DynareOptions.plot_shock_decomp.use_shock_groups;
                 mydata.shock_group = shock_groups.(shock_ind{ic});