diff --git a/call_abq.m b/call_abq.m
index 2f32ccb..a2f5adb 100644
--- a/call_abq.m
+++ b/call_abq.m
@@ -39,7 +39,7 @@
 fclose(fLoad);
 
 % Run analysis via system call
-[~] = system('abaqus job=job input=template >job.log');
+[~,~] = system('abaqus job=job input=template >job.log');
 
 % Load results from output file
 Ut = load_fil('job.fil');
diff --git a/main.m b/main.m
index d786df8..60f4b7e 100644
--- a/main.m
+++ b/main.m
@@ -24,9 +24,12 @@
 [P_2,M_2,Q_2] = compute_mtx(nel, E2_min, E2_max);
 
 %% Data for 3D mechanical Problem
+if non_intrusive == 1
+    delete *.mtx
+end
 if not(exist('K_1_STIF1.mtx','file') && exist('K_2_STIF1.mtx','file'))
-    [~] = system('abaqus job=K_1 input=K1 >K_1.log');
-    [~] = system('abaqus job=K_2 input=K2 >K_2.log');
+    [~,~] = system('abaqus job=K_1 input=K1 >K_1.log');
+    [~,~] = system('abaqus job=K_2 input=K2 >K_2.log');
     delete K_1.* K_2.*
 end