diff --git a/ioctl.c b/ioctl.c
index be0bbd4..c765287 100644
--- a/ioctl.c
+++ b/ioctl.c
@@ -86,12 +86,23 @@
         ioctl_argp_save = ioctl_argp = ioctl_args;
         rem = length;
         while(optind < argc) {
-            uint64_t tmp = strtoull(argv[optind], NULL, 0);
+            uint64_t tmp_64 = strtoull(argv[optind], NULL, 0);
+            uint32_t tmp_32 = tmp_64;
             if(rem < arg_size) {
                 fprintf(stderr, "%s: too many arguments\n", argv[0]);
                 exit(1);
             }
-            memcpy(ioctl_argp, &tmp, arg_size);
+            switch (arg_size) {
+            case sizeof(tmp_64):
+              memcpy(ioctl_argp, &tmp_64, sizeof(tmp_64));
+              break;
+            case sizeof(tmp_32):
+              memcpy(ioctl_argp, &tmp_32, sizeof(tmp_32));
+              break;
+            default:
+              fprintf(stderr, "%s: unhandled arg_size\n", argv[0]);
+              exit(1);
+            }
             ioctl_argp += arg_size;
             rem -= arg_size;
             optind++;