diff --git a/Processors/6502Mk2/6502Mk2.hpp b/Processors/6502Mk2/6502Mk2.hpp
index 88af967b0..99a5aeee8 100644
--- a/Processors/6502Mk2/6502Mk2.hpp
+++ b/Processors/6502Mk2/6502Mk2.hpp
@@ -114,9 +114,9 @@ struct NoValue {
 class Writeable {
 public:
 	uint8_t operator=(const uint8_t value) {
-		if constexpr (requires{did_write_;}) {
-			did_write_ = true;
-		}
+		#ifndef NDEBUG
+		did_write_ = true;
+		#endif
 		return result_ = value;
 	}
 	operator uint8_t() const {
@@ -126,17 +126,9 @@ public:
 
 private:
 	uint8_t result_;
-	friend struct WriteableReader;
-#ifndef NDEBUG
+	#ifndef NDEBUG
 	bool did_write_ = false;
-#endif
-};
-
-struct WriteableReader {
-	static void assign(uint8_t &lhs, const Writeable rhs) {
-		lhs = rhs;
-	}
-	static void assign(const uint8_t &, const Writeable) {}
+	#endif
 };
 
 template <BusOperation, typename Enable = void> struct Value;
diff --git a/Processors/6502Mk2/Implementation/6502.hpp b/Processors/6502Mk2/Implementation/6502.hpp
index 67e42cdc4..baf66e338 100644
--- a/Processors/6502Mk2/Implementation/6502.hpp
+++ b/Processors/6502Mk2/Implementation/6502.hpp
@@ -29,6 +29,13 @@ void Processor<model, Traits>::run_for(const Cycles cycles) {
 	Storage::cycles_ += cycles;
 	if(Storage::cycles_ <= Cycles(0)) return;
 
+	struct WriteableReader {
+		static void assign(uint8_t &lhs, const Data::Writeable rhs) {
+			lhs = rhs;
+		}
+		static void assign(const uint8_t &, const Data::Writeable) {}
+	};
+
 	#define restore_point()	(__COUNTER__ + int(ResumePoint::Max) + int(AddressingMode::Max))
 
 	#define join(a, b) 			a##b
@@ -62,7 +69,7 @@ void Processor<model, Traits>::run_for(const Cycles cycles) {
 			} else {																					\
 				Data::Writeable target;																	\
 				Storage::cycles_ -= Storage::bus_handler_.template perform<type>(addr, target);			\
-				Data::WriteableReader::assign(value, target);											\
+				WriteableReader::assign(value, target);													\
 			}																							\
 		} else {																						\
 			Storage::cycles_ -= Storage::bus_handler_.template perform<type>(addr, value);				\