diff --git a/@GUI/close_fig.m b/@GUI/close_fig.m
index b531dec9b13e276a0e36e7e27a8a68041f845a23..e4da8158b008d91db5e2da8d1518d90ecd0fb8cd 100644
--- a/@GUI/close_fig.m
+++ b/@GUI/close_fig.m
@@ -12,6 +12,7 @@
 function [] = close_fig(object,src,event)
 if (object.validation_report_handle ~= 0)
     delete(object.validation_report_handle);
+    object.validation_report_handle = 0;
 end
 object.save_data;
 object.Data.open = 0;
diff --git a/@GUI/cvc_ext_call.m b/@GUI/cvc_ext_call.m
index 0740110b1af794242ffd6daf8c04c1b78940c292..64aad6d502949abd88d73bef9deeeae5a5cc16c6 100644
--- a/@GUI/cvc_ext_call.m
+++ b/@GUI/cvc_ext_call.m
@@ -7,6 +7,7 @@ object.save_call([],[]);
 object.save_data;
 if (object.validation_report_handle ~= 0)
     delete(object.validation_report_handle);
+    object.validation_report_handle = 0;
 end
 error = object.check_call([],2);
 
diff --git a/@GUI/pvs_ext_call.m b/@GUI/pvs_ext_call.m
index b5da72e9a333b3cff3655e30d5237a18f71e336d..b9d855999298e69cfa9cb18c72e025817cd57758 100644
--- a/@GUI/pvs_ext_call.m
+++ b/@GUI/pvs_ext_call.m
@@ -13,6 +13,7 @@ object.save_call([],[]);
 object.save_data;
 if (object.validation_report_handle ~= 0)
     delete(object.validation_report_handle);
+    object.validation_report_handle = 0;
 end
 error = object.check_call([],2);