2 files changed, 4 insertions, 0 deletions
diff --git a/NEWS b/NEWS
index 030432f..0afee1b 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,9 @@ GNU diffutils NEWS                                    -*- outline -*-
 
   diff no longer mishandles line numbers exceeding 2**31 on Mingw-w64.
 
+  the ---presume-output-tty (ostensibly test-only) option would cause
+  diff --color to read an uninitialized variable
+
 ** Performance changes
 
   diff's default algorithm has been tweaked to deal better with larger
diff --git a/src/diff.c b/src/diff.c
index efcedf9..76851ac 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -296,6 +296,7 @@ main (int argc, char **argv)
   ignore_regexp_list.buf = &ignore_regexp;
   re_set_syntax (RE_SYNTAX_GREP | RE_NO_POSIX_BACKTRACKING);
   excluded = new_exclude ();
+  presume_output_tty = false;
 
   /* Decode the options.  */