diff --git a/include/register.h b/include/register.h
index 21731b0..f81849a 100644
--- a/include/register.h
+++ b/include/register.h
@@ -36,7 +36,7 @@ struct Register {
     Register &operator=(const Register &rhs) = delete;
 
     template <concepts::bit_convertible <_Len> _Tp>
-    void operator <= (_Tp &&value) {
+    void operator <= (const _Tp &value) {
         debug::assert(!this->_M_assigned, "Register is double assigned in this cycle.");
         this->_M_assigned = true;
         this->_M_new = static_cast <max_size_t> (value);