diff --git a/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift b/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift
index caea8529b..7fe5feec9 100644
--- a/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift	
+++ b/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift	
@@ -459,21 +459,59 @@ class WDC65816AddressingTests: XCTestCase {
 		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 
-	// TODO: all tests from this point downward.
-
-	func testLong() {
+	func testAbsoluteLong() {
 		// "If the m flag is 0, then LDA $12FFFF loads the low byte of the data from address $12FFFF,
 		// and the high byte from address $130000."
+		let machine = machine16()
+
+		machine.setValue(0xab, forAddress: 0x12ffff)
+		machine.setValue(0xcd, forAddress: 0x130000)
+
+		// LDA $12ffff; NOP
+		machine.setData(Data([0xaf, 0xff, 0xff, 0x12, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 7)
+
+		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 
-	func testLongX() {
+	func testAbsoluteLongX() {
 		// "If the X register is $000A and the m flag is 0, then LDA $12FFFE,X loads the low byte of
 		// the data from address $130008, and the high byte from address $130009."
+		let machine = machine16()
+
+		machine.setValue(0x000a, for: .X)
+
+		machine.setValue(0xab, forAddress: 0x130008)
+		machine.setValue(0xcd, forAddress: 0x130009)
+
+		// LDA $12fffe, x; NOP
+		machine.setData(Data([0xbf, 0xfe, 0xff, 0x12, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 7)
+
+		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 
 	func testStackS() {
 		// "If the S register is $FF10 and the m flag is 0, then LDA $FA,S loads the low byte
 		// of the data from address $00000A, and the high byte from address $00000B."
+		let machine = machine16()
+
+		machine.setValue(0xff10, for: .stackPointer)
+
+		machine.setValue(0xab, forAddress: 0x000a)
+		machine.setValue(0xcd, forAddress: 0x000b)
+
+		// LDA $fa, s; NOP
+		machine.setData(Data([0xa3, 0xfa, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 7)
+
+		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 
 	func testIndirectStackSY() {
@@ -484,5 +522,24 @@ class WDC65816AddressingTests: XCTestCase {
 		//	* $00000B contains $FF
 		// then LDA ($FA,S),Y loads the low byte of the data from address $130040, and the high
 		// byte from $130041."
+		let machine = machine16()
+
+		machine.setValue(0xff10, for: .stackPointer)
+		machine.setValue(0x0050, for: .Y)
+		machine.setValue(0x12, for: .dataBank)
+
+		machine.setValue(0xf0, forAddress: 0x000a)
+		machine.setValue(0xff, forAddress: 0x000b)
+
+		machine.setValue(0xab, forAddress: 0x130040)
+		machine.setValue(0xcd, forAddress: 0x130041)
+
+		// LDA ($fa, s), y; NOP
+		machine.setData(Data([0xb3, 0xfa, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 9)
+
+		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 }
diff --git a/Processors/65816/Implementation/65816Implementation.hpp b/Processors/65816/Implementation/65816Implementation.hpp
index 2cbb792bb..5c99ffe34 100644
--- a/Processors/65816/Implementation/65816Implementation.hpp
+++ b/Processors/65816/Implementation/65816Implementation.hpp
@@ -360,8 +360,9 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
 			continue;
 
 			case OperationConstructStackRelativeIndexedIndirect:
-				data_address_ = (instruction_buffer_.value + y()) & 0xffff;
+				data_address_ = data_bank_ + data_buffer_.value + y();
 				data_address_increment_mask_ = 0xff'ff'ff;
+				data_buffer_.clear();
 			continue;
 
 			case OperationConstructPER:
diff --git a/Processors/65816/Implementation/65816Storage.hpp b/Processors/65816/Implementation/65816Storage.hpp
index 6758d07f8..7698345e0 100644
--- a/Processors/65816/Implementation/65816Storage.hpp
+++ b/Processors/65816/Implementation/65816Storage.hpp
@@ -325,6 +325,7 @@ struct ProcessorStorage {
 
 		private:
 			uint8_t *byte(int pointer) {
+				assert(pointer >= 0 && pointer < 4);
 				#if TARGET_RT_BIG_ENDIAN
 					return reinterpret_cast<uint8_t *>(&value) + (3 ^ pointer);
 				#else