1 files changed, 1 insertions, 1 deletions

diff --git a/src/msdos.c b/src/msdos.c
index 180e8a42683..a1113cc4d4c 100644
--- a/src/msdos.c
+++ b/src/msdos.c
@@ -1056,7 +1056,7 @@ IT_write_glyphs (struct glyph *str, int str_len)
                  terminal_coding with Vdos_unsupported_char_glyph.  */
               if (*conversion_buffer == '?')
                 {
-                  char *cbp = conversion_buffer;
+                  unsigned char *cbp = conversion_buffer;
 
                   while (cbp < conversion_buffer + enclen && *cbp == '?')
                     *cbp++ = unsupported_char;