1 files changed, 1 insertions, 1 deletions

diff --git a/lib-src/emacsclient.c b/lib-src/emacsclient.c
index b63a4d2bf50..988bfc4fd4d 100644
--- a/lib-src/emacsclient.c
+++ b/lib-src/emacsclient.c
@@ -425,7 +425,7 @@ main (argc, argv)
       if (*argv[i] == '+')
         {
           char *p = argv[i] + 1;
-          while (isdigit (*p) || *p == ':') p++;
+          while (isdigit ((unsigned char) *p) || *p == ':') p++;
           if (*p != 0)
             fprintf (out, "%s/", quote_file_name (cwd));
         }