diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index ffd6cfd3cbf..0cfc80de21b 100644
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,8 @@
+2015-08-09  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
+
+	PR libfortran/66936
+	* io/unix.c (__MINGW32__): Undefine HAVE_UMASK.
+
 2015-08-07  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
 
 	PR libfortran/66458
diff --git a/libgfortran/io/unix.c b/libgfortran/io/unix.c
index a1ce9a3ffe7..4d8726c494b 100644
--- a/libgfortran/io/unix.c
+++ b/libgfortran/io/unix.c
@@ -101,6 +101,12 @@ id_from_fd (const int fd)
 }
 
 #endif /* HAVE_WORKING_STAT */
+
+
+/* On mingw, we don't use umask in tempfile_open(), because it
+   doesn't support the user/group/other-based permissions.  */
+#undef HAVE_UMASK
+
 #endif /* __MINGW32__ */