diff --git a/include/date.cpp b/include/date.cpp
index 0950f6801..754c53f78 100755
--- a/include/date.cpp
+++ b/include/date.cpp
@@ -191,8 +191,16 @@ int TDate::wday() const
   return ((d + 2*m + 3*(m+1)/5 + y + y/4 - y/100 + y/400) % 7) + 1; // Pure magic
 }
 
-void  TDate::set_day(int n)   { _val = makedata(n, month(), year()); }  
-void  TDate::set_month(int n) { _val = makedata(day(), n, year());   }  
+void  TDate::set_day(int n)   
+{ 
+   CHECK(n > 0 && n < 32, "TDate::set_day: giorno insensato");
+  _val = makedata(n, month(), year()); 
+}  
+void  TDate::set_month(int n) 
+{ 
+  CHECK(n > 0 && n < 13, "TDate::set_month: mese impossibile");
+  _val = makedata(day(), n, year());   
+}  
 void  TDate::set_year(int n)  { _val = makedata(day(), month(), n);  }  
 
 TDate::operator const char*() const
diff --git a/include/msksheet.cpp b/include/msksheet.cpp
index fdefd5cf3..c873c591a 100755
--- a/include/msksheet.cpp
+++ b/include/msksheet.cpp
@@ -1335,7 +1335,8 @@ void TSpreadsheet::on_idle()
 {
   if (_needs_update >= 0)
   {
-    update_rec(_needs_update);
+    if (_needs_update < items()) 
+      update_rec(_needs_update);
     _needs_update = -1;
   }
 }