1 files changed, 1 insertions, 1 deletions

diff --git a/src/arm/gnunet-service-arm.c b/src/arm/gnunet-service-arm.c
index a298576b0..52c7dec20 100644
--- a/src/arm/gnunet-service-arm.c
+++ b/src/arm/gnunet-service-arm.c
@@ -382,7 +382,7 @@ start_process (struct ServiceList *sl)
           while (NULL != (optpos = strstr (options, "$")))
             {
               optend = optpos + 1;
-              while (isupper (*optend)) optend++;             
+              while (isupper ( (unsigned char) *optend)) optend++;            
               b = *optend;
               if ('\0' == b)
                 next = "";