diff --git a/test_libug_receiver.c b/test_libug_receiver.c
index 248817389..0ee8f921b 100644
--- a/test_libug_receiver.c
+++ b/test_libug_receiver.c
@@ -72,7 +72,7 @@ int main(int argc, char *argv[]) {
                 init_params.sender = argv[0];
                 if (strchr(argv[0], ':') != NULL) {
                         char *port_str = strchr(argv[0], ':') + 1;
-                        *strchr(argv[1], ':') = '\0';
+                        *strchr(argv[0], ':') = '\0';
                         init_params.port = atoi(port_str);
                 }
         }