diff --git a/src/lib/progbar.c b/src/lib/progbar.c
index 6ccb889d8..034a697a4 100644
--- a/src/lib/progbar.c
+++ b/src/lib/progbar.c
@@ -8,7 +8,7 @@ ncprogbar* ncprogbar_create(ncplane* n, const ncprogbar_options* opts){
     opts = &default_opts;
   }
   if(opts->flags > (NCPROGBAR_OPTION_RETROGRADE << 1u)){
-    logwarn(ncplane_notcurses(n), "Invalid flags %016lx\n", opts->flags);
+    logwarn(ncplane_notcurses(n), "Invalid flags %016jx\n", (uintmax_t)opts->flags);
   }
   ncprogbar* ret = malloc(sizeof(*ret));
   if(ret){