diff --git a/ve/velib02.cpp b/ve/velib02.cpp
index 4e66e875e..a99557d01 100755
--- a/ve/velib02.cpp
+++ b/ve/velib02.cpp
@@ -1039,14 +1039,17 @@ void TRiga_documento::autosave(TSheet_field& f)
           const short cms_start = doc_mask.cms_start();
           const short cms_end = doc_mask.cms_end();
           codcms.cut(0);
-          for (short j = cms_start; j <= cms_end; j++)
+          if (cms_start > 0 && cms_end >= cms_start)
           {
-            const TEdit_field& fld = doc_mask.efield(j);
-            TString80 str = fld.get();
-            str.rpad(fld.size());
-            codcms << str;
+            for (short j = cms_start; j <= cms_end; j++)
+            {
+              const TEdit_field& fld = doc_mask.efield(j);
+              TString80 str = fld.get();
+              str.rpad(fld.size());
+              codcms << str;
+            }
+            codcms.rtrim();
           }
-          codcms.rtrim();
         }
         if (codcms.full() && codiva.full())
         {