diff --git a/include/nil/crypto3/zk/snark/arithmetization/plonk/constraint_system.hpp b/include/nil/crypto3/zk/snark/arithmetization/plonk/constraint_system.hpp
index e313b61d..46f321a8 100644
--- a/include/nil/crypto3/zk/snark/arithmetization/plonk/constraint_system.hpp
+++ b/include/nil/crypto3/zk/snark/arithmetization/plonk/constraint_system.hpp
@@ -37,6 +37,7 @@
 
 #include <cstdlib>
 #include <vector>
+#include <unordered_set>
 
 #include <nil/crypto3/zk/snark/arithmetization/plonk/gate.hpp>
 #include <nil/crypto3/zk/snark/arithmetization/plonk/constraint.hpp>