diff --git a/barretenberg/cpp/src/barretenberg/proof_system/types/circuit_type.hpp b/barretenberg/cpp/src/barretenberg/proof_system/types/circuit_type.hpp
index 71960c191195..f1fb50c36274 100644
--- a/barretenberg/cpp/src/barretenberg/proof_system/types/circuit_type.hpp
+++ b/barretenberg/cpp/src/barretenberg/proof_system/types/circuit_type.hpp
@@ -3,6 +3,7 @@
 #include <cstdint>
 
 namespace proof_system {
+// TODO(#731): Changing the explicit value of these enum elements breaks brittle and outdated tests in circuits/cpp.
 enum class CircuitType : uint32_t { STANDARD = 0, ULTRA = 2, UNDEFINED = 3 };
 
 template <typename T, typename... U>