2 files changed, 7 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index a3747844c65..c4e57537522 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,9 @@
 2013-03-24  Ken Brown  <kbrown@cornell.edu>
 
+        * w32fns.c (emacs_abort) [CYGWIN]: Define `_open' as a macro to
+        fix compilation on 64-bit Cygwin, where underscores are not
+        automatically prepended.
+
         * w32term.c (w32_initialize): Silence compiler warning.
 
 2013-03-23  Eli Zaretskii  <eliz@gnu.org>
diff --git a/src/w32fns.c b/src/w32fns.c
index 4c47465e67b..88141893445 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -7759,6 +7759,9 @@ emacs_abort (void)
 #endif
             if (stderr_fd >= 0)
               write (stderr_fd, "\r\nBacktrace:\r\n", 14);
+#ifdef CYGWIN
+#define _open open
+#endif
             errfile_fd = _open ("emacs_backtrace.txt", O_RDWR | O_CREAT | O_BINARY, S_IREAD | S_IWRITE);
             if (errfile_fd >= 0)
               {