diff --git a/compat/winansi.c b/compat/winansi.c
index 664b672d40f85f..986bfb30cf5b06 100644
--- a/compat/winansi.c
+++ b/compat/winansi.c
@@ -505,6 +505,8 @@ static HANDLE swap_osfhnd(int fd, HANDLE new_handle)
 	 */
 	close(new_fd);
 
+	if (fd == 2)
+		setvbuf(stderr, NULL, _IONBF, BUFSIZ);
 	fd_is_interactive[fd] |= FD_SWAPPED;
 
 	return duplicate;
@@ -555,6 +557,8 @@ static void detect_msys_tty(int fd)
 			!wcsstr(name, L"-pty"))
 		return;
 
+	if (fd == 2)
+		setvbuf(stderr, NULL, _IONBF, BUFSIZ);
 	fd_is_interactive[fd] |= FD_MSYS;
 }