1 files changed, 2 insertions, 1 deletions
diff --git a/src/item.cc b/src/item.cc
index c5db3cad..052d70eb 100644
--- a/src/item.cc
+++ b/src/item.cc
@@ -157,7 +157,8 @@ void item_t::parse_tags(const char * p,
   if (! std::strchr(p, ':')) {
     if (const char * b = std::strchr(p, '[')) {
       if (*(b + 1) != '\0' &&
-          (std::isdigit(*(b + 1)) || *(b + 1) == '=')) {
+          (std::isdigit(static_cast<unsigned char>(*(b + 1))) ||
+           *(b + 1) == '=')) {
         if (const char * e = std::strchr(b, ']')) {
           char buf[256];
           std::strncpy(buf, b + 1, static_cast<std::size_t>(e - b - 1));