diff --git a/src/register/hei_operator_register.hpp b/src/register/hei_operator_register.hpp
index 5c225b1..5e40358 100644
--- a/src/register/hei_operator_register.hpp
+++ b/src/register/hei_operator_register.hpp
@@ -381,7 +381,7 @@
     ConstantRegister& operator=(const ConstantRegister& r) = delete;
 
     /** @brief Overloaded from parent class. */
-    const BitString* getBitString(const Chip& i_chip) const override
+    const BitString* getBitString(const Chip&) const override
     {
         return &iv_result;
     }