1 files changed, 1 insertions, 1 deletions

diff --git a/bzlib.c b/bzlib.c
index 2178655..100873c 100644
--- a/bzlib.c
+++ b/bzlib.c
@@ -1408,7 +1408,7 @@ BZFILE * bzopen_or_bzdopen
       case 's':
          smallMode = 1; break;
       default:
-         if (isdigit((int)(*mode))) {
+         if (isdigit((unsigned char)(*mode))) {
             blockSize100k = *mode-BZ_HDR_0;
          }
       }