Index: src/diff.c
===================================================================
--- src/diff.c.orig	2010-08-20 12:12:57.564209017 +0200
+++ src/diff.c	2010-08-20 12:14:04.231266936 +0200
@@ -1087,7 +1087,7 @@ compare_files (struct comparison const *
 	  else if (strcmp (cmp.file[f].name, "-") == 0)
 	    {
 	      cmp.file[f].desc = STDIN_FILENO;
-	      if (binary && ! isatty (STDIN_FILENO))
+	      if (O_BINARY && binary && ! isatty (STDIN_FILENO))
 		freopen (NULL, "rb", stdin);
 	      if (fstat (STDIN_FILENO, &cmp.file[f].stat) != 0)
 		cmp.file[f].desc = ERRNO_ENCODE (errno);