diff --git a/Z80/fusetest_Z80/FuseTestRunner.cpp b/Z80/fusetest_Z80/FuseTestRunner.cpp
index 10a11cf..6c02004 100644
--- a/Z80/fusetest_Z80/FuseTestRunner.cpp
+++ b/Z80/fusetest_Z80/FuseTestRunner.cpp
@@ -79,15 +79,15 @@ EightBit::MemoryMapping Fuse::TestRunner::mapping(uint16_t address) {
 	const bool io = m_cpu.requestingIO();
 	if (io) {
 
-		m_ports.setAccessType(EightBit::InputOutput::AccessType::Unknown);
+		m_ports.accessType() = EightBit::InputOutput::AccessType::Unknown;
 
 		const bool reading = m_cpu.requestingRead();
 		if (reading)
-			m_ports.setAccessType(EightBit::InputOutput::AccessType::Reading);
+			m_ports.accessType() = EightBit::InputOutput::AccessType::Reading;
 
 		const bool writing = m_cpu.requestingWrite();
 		if (writing)
-			m_ports.setAccessType(EightBit::InputOutput::AccessType::Writing);
+			m_ports.accessType() = EightBit::InputOutput::AccessType::Writing;
 
 		return {
 			m_ports,
diff --git a/inc/InputOutput.h b/inc/InputOutput.h
index afed374..df9cf77 100644
--- a/inc/InputOutput.h
+++ b/inc/InputOutput.h
@@ -20,24 +20,24 @@ namespace EightBit {
 		int load(std::string path, int writeOffset = 0, int readOffset = 0, int limit = -1) override;
 		int load(const std::vector<uint8_t>& bytes, int writeOffset = 0, int readOffset = 0, int limit = -1) override;
 
-		[[nodiscard]] AccessType getAccessType() const noexcept { return m_access; }
-		void setAccessType(AccessType value) noexcept { m_access = value; }
+		[[nodiscard]] const AccessType& accessType() const noexcept { return m_access; }
+		[[nodiscard]] AccessType& accessType() noexcept { return m_access; }
 
-		auto readPort(uint8_t port, AccessType access) {
-			setAccessType(access);
+		[[nodiscard]] auto readPort(uint8_t port, AccessType access) {
+			accessType() = access;
 			return reference(port);
 		}
 
-		auto readInputPort(uint8_t port) { return readPort(port, AccessType::Reading); }
-		auto readOutputPort(uint8_t port) { return readPort(port, AccessType::Writing); }
+		[[nodiscard]] auto readInputPort(uint8_t port) { return readPort(port, AccessType::Reading); }
+		[[nodiscard]] auto readOutputPort(uint8_t port) { return readPort(port, AccessType::Writing); }
 
 		void writePort(uint8_t port, uint8_t value, AccessType access) {
-			setAccessType(access);
+			accessType() = access;
 			reference(port) = value;
 		}
 
-		auto writeInputPort(uint8_t port, uint8_t value) { return writePort(port, value, AccessType::Reading); }
-		auto writeOutputPort(uint8_t port, uint8_t value) { return writePort(port, value,  AccessType::Writing); }
+		void writeInputPort(uint8_t port, uint8_t value) { writePort(port, value, AccessType::Reading); }
+		void writeOutputPort(uint8_t port, uint8_t value) { writePort(port, value,  AccessType::Writing); }
 
 	protected:
 		void poke(uint16_t address, uint8_t value) override;
diff --git a/src/InputOutput.cpp b/src/InputOutput.cpp
index 0265220..8d60061 100644
--- a/src/InputOutput.cpp
+++ b/src/InputOutput.cpp
@@ -15,12 +15,11 @@ uint8_t EightBit::InputOutput::peek(uint16_t) const {
 
 uint8_t& EightBit::InputOutput::reference(uint16_t address) {
 	const auto port = register16_t(address).low;
-	switch (getAccessType()) {
+	switch (accessType()) {
 	case AccessType::Reading:
 		return m_input.reference(port);
 	case AccessType::Writing:
 		return m_output.reference(port);
-	case AccessType::Unknown:
 	default:
 		throw std::logic_error("Unknown I/O access type.");
 	}