--- a/inst/@dataframe/subsasgn.m
+++ b/inst/@dataframe/subsasgn.m
@@ -117,14 +117,14 @@
           endif
           return
 
-	case "header"
+        case "header"
           if (length (S) > 1)
             df._header = feval (@subsasgn, df._header, S(2:end), RHS);
           else
             df._header = RHS;
           endif
           return
-	  
+          
         case "comment"
           if (length (S) > 1)
             df._cmt = feval (@subsasgn, df._cmt, S(2:end), RHS);