--- wdiff.c.old	2004-10-12 14:23:32.000000000 +0100
+++ wdiff.c	2004-10-12 14:36:55.000000000 +0100
@@ -182,7 +182,7 @@
 SIDE *left_side = &side_array[0];
 SIDE *right_side = &side_array[1];
 
-FILE *input_file;		/* stream being produced by diff */
+FILE *input_file = NULL;	/* stream being produced by diff */
 int character;			/* for reading input_file */
 char directive;			/* diff directive character */
 int argument[4];		/* four diff directive arguments */
@@ -910,7 +910,11 @@
 static void
 complete_input_program (void)
 {
-  fclose (input_file);
+  if (input_file != NULL)
+    {
+      fclose (input_file);
+      input_file = NULL;
+    }
   wait (NULL);
 }
 
@@ -1303,6 +1307,7 @@
       initialize_strings ();
       reformat_diff_output ();
       fclose (input_file);
+      input_file = NULL;
     }
 
   /* Clean up.  Beware that input_file and output_file might not exist,