diff --git a/Inputs/Joystick.hpp b/Inputs/Joystick.hpp
index fc9f32213..57ee46824 100644
--- a/Inputs/Joystick.hpp
+++ b/Inputs/Joystick.hpp
@@ -36,7 +36,10 @@ class Joystick {
 				// Fire buttons.
 				Fire,
 				// Other labelled keys.
-				Key
+				Key,
+
+				// The maximum value this enum can contain.
+				Max = Key
 			};
 			const Type type;
 
diff --git a/Machines/Amiga/Chipset.cpp b/Machines/Amiga/Chipset.cpp
index 0e28b27d2..1b2216c86 100644
--- a/Machines/Amiga/Chipset.cpp
+++ b/Machines/Amiga/Chipset.cpp
@@ -1270,7 +1270,7 @@ void Chipset::Mouse::set_button_pressed(int button, bool is_set) {
 	}
 }
 
-uint8_t Chipset::Mouse::get_cia_button() {
+uint8_t Chipset::Mouse::get_cia_button() const {
 	return cia_state_;
 }
 
@@ -1319,5 +1319,46 @@ uint16_t Chipset::Mouse::get_position() {
 	);
 }
 
+// MARK: - Joystick.
+
+void Chipset::Joystick::did_set_input(const Input &input, bool is_active) {
+	// Accumulate state.
+	inputs_[input.type] = is_active;
+
+	// Determine what that does to the two position bits.
+	const auto low =
+		(inputs_[Input::Type::Down] ^ inputs_[Input::Type::Right]) |
+		(inputs_[Input::Type::Right] << 1);
+	const auto high =
+		(inputs_[Input::Type::Up] ^ inputs_[Input::Type::Left]) |
+		(inputs_[Input::Type::Left] << 1);
+
+	// Ripple upwards if that affects the mouse position counters.
+	const uint8_t previous_low = position_ & 3;
+	uint8_t low_upper = (position_ >> 2) & 0x3f;
+	const uint8_t previous_high = (position_ >> 8) & 3;
+	uint8_t high_upper = (position_ >> 10) & 0x3f;
+
+	if(!low && previous_low == 3) ++low_upper;
+	if(!previous_low && low == 3) --low_upper;
+	if(!high && previous_high == 3) ++high_upper;
+	if(!previous_high && high == 3) --high_upper;
+
+	position_ = uint16_t(
+		low | ((low_upper & 0x3f) << 2) |
+		(high << 8) | ((high_upper & 0x3f) << 10)
+	);
+}
+
+uint16_t Chipset::Joystick::get_position() const {
+	return position_;
+}
+
+uint8_t Chipset::Joystick::get_cia_button() const {
+	return inputs_[Input::Type::Fire] ? 0xbf : 0xff;
+}
+
+// MARK: - Synchronisation.
+
 void Chipset::flush() {
 }
diff --git a/Machines/Amiga/Chipset.hpp b/Machines/Amiga/Chipset.hpp
index aba4e3d25..558c66aa2 100644
--- a/Machines/Amiga/Chipset.hpp
+++ b/Machines/Amiga/Chipset.hpp
@@ -19,6 +19,7 @@
 #include "../../ClockReceiver/ClockingHintSource.hpp"
 #include "../../ClockReceiver/JustInTime.hpp"
 #include "../../Components/6526/6526.hpp"
+#include "../../Inputs/Joystick.hpp"
 #include "../../Inputs/Mouse.hpp"
 #include "../../Outputs/CRT/CRT.hpp"
 #include "../../Processors/68000/68000.hpp"
@@ -336,7 +337,7 @@ class Chipset: private ClockingHint::Observer {
 		class Mouse: public Inputs::Mouse {
 			public:
 				uint16_t get_position();
-				uint8_t get_cia_button();
+				uint8_t get_cia_button() const;
 
 			private:
 				int get_number_of_buttons() final;
@@ -352,6 +353,22 @@ class Chipset: private ClockingHint::Observer {
 	public:
 		Inputs::Mouse &get_mouse();
 
+		// MARK: - Joystick.
+	private:
+		class Joystick: public Inputs::ConcreteJoystick {
+			public:
+				Joystick();
+
+				uint16_t get_position() const;
+				uint8_t get_cia_button() const;
+
+			private:
+				void did_set_input(const Input &input, bool is_active) final;
+
+				bool inputs_[Joystick::Input::Type::Max]{};
+				uint16_t position_ = 0;
+		};
+
 		// MARK: - CIAs.
 	private:
 		class DiskController;