diff --git a/include/relation.cpp b/include/relation.cpp
index a76841393..1733636cc 100755
--- a/include/relation.cpp
+++ b/include/relation.cpp
@@ -2451,12 +2451,18 @@ void TFieldref::write(const char* val, TRectype& rec) const
     buffer = rec.get(_name);
     if (_to <= _from)
       ((TFieldref*)this)->_to = rec.length(_name);
-    buffer.overwrite(val, _from, _to - _from);
-    rec.put(_name, buffer);
+    if (val && *val)
+    {
+      buffer.overwrite(val, _from, _to - _from);
+      rec.put(_name, buffer);
+    }
   }
   else  
   {
-    rec.put(_name, val);
+    if (val && *val)
+      rec.put(_name, val);
+    else
+      rec.zero(_name);
   }  
 }
 
diff --git a/include/strings.cpp b/include/strings.cpp
index a4e9a056a..3f8079076 100755
--- a/include/strings.cpp
+++ b/include/strings.cpp
@@ -975,7 +975,8 @@ TString& TString::overwrite(
   //
   // @xref <mf TString::insert>
 {
-  if (lung == 0) lung=strlen(s);
+  if (lung == 0 && s != NULL) 
+    lung=strlen(s);
   if (s || lung)
   {
     const int l = len();