--- file_not_specified_in_diff	
+++ file_not_specified_in_diff	
@@ -170,14 +170,21 @@ gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
   size_t len;
   int eof, readlen;
 
-  sgr = gr;
+  if (old_gr == NULL && gr == NULL)
+      return (-1);
+
+  sgr = old_gr;
+  /* deleting a group */
   if (gr == NULL) {
     line = NULL;
-    if (old_gr == NULL)
+  } else {
+    if ((line = gr_make(gr)) == NULL)
       return (-1);
-    sgr = old_gr;
-  } else if ((line = gr_make(gr)) == NULL)
-    return (-1);
+  }
+
+  /* adding a group */
+  if (sgr == NULL)
+    sgr = gr;
 
   eof = 0;
   len = 0;