diff --git a/components/rx/trunk/rxdb/rxdbgrid.pas b/components/rx/trunk/rxdb/rxdbgrid.pas
index f1b06bba1..7b941ba67 100644
--- a/components/rx/trunk/rxdb/rxdbgrid.pas
+++ b/components/rx/trunk/rxdb/rxdbgrid.pas
@@ -5214,6 +5214,7 @@ var
   j, L, R: integer;
   S: string;
 begin
+  C:=nil;
   if (rdgColSpanning in OptionsRx) then
     if IsMerged(aCol, L, R, C) then
       aCol:=L;