diff --git a/src/fractal.cpp b/src/fractal.cpp
index cee25b6..b51b740 100644
--- a/src/fractal.cpp
+++ b/src/fractal.cpp
@@ -23,6 +23,9 @@ group_id_t ruleset_t::add_group_characteristic(const etl::ivector<token_id_t>& t
 	if (m_group_characteristics.full()) {
 		throw mtl::length_error();
 	}
+	if (tokens.size() > g_max_cgroup_tokens) {
+		throw mtl::length_error();
+	}
 
 	m_group_characteristics.push_back(group_characteristic_t());
 	group_characteristic_t& chr = m_group_characteristics.back();