diff --git a/OSBindings/Mac/Clock SignalTests/Z80MemptrTests.swift b/OSBindings/Mac/Clock SignalTests/Z80MemptrTests.swift
index 75bfde211..6b6c108e2 100644
--- a/OSBindings/Mac/Clock SignalTests/Z80MemptrTests.swift	
+++ b/OSBindings/Mac/Clock SignalTests/Z80MemptrTests.swift	
@@ -167,10 +167,28 @@ class Z80MemptrTests: XCTestCase {
 		}
 	}
 
-	/* TODO:
-		ADD/ADC/SBC rp1,rp2
-			MEMPTR = rp1_before_operation + 1
-	*/
+	// ADD/ADC/SBC dest, src
+	func testADDADCSBCrr() {
+		// MEMPTR = dest prior to modification + 1
+		let addProgram: [UInt8] = [
+			0x09
+		]
+		let adcProgram: [UInt8] = [
+			0xed, 0x4a
+		]
+		let sbcProgram: [UInt8] = [
+			0xed, 0x42
+		]
+
+		for addr in 0 ..< 65536 {
+			let expectedResult = UInt16((addr + 1) & 0xffff)
+			machine.setValue(UInt16(addr), for: .HL)
+
+			XCTAssertEqual(test(program: addProgram, length: 11, initialValue: 0xffff), expectedResult)
+			XCTAssertEqual(test(program: adcProgram, length: 15, initialValue: 0xffff), expectedResult)
+			XCTAssertEqual(test(program: sbcProgram, length: 15, initialValue: 0xffff), expectedResult)
+		}
+	}
 
 	// RLD/RRD
 	func testRLDRRD() {
diff --git a/Processors/Z80/Z80.hpp b/Processors/Z80/Z80.hpp
index b99b3446c..ab842695e 100644
--- a/Processors/Z80/Z80.hpp
+++ b/Processors/Z80/Z80.hpp
@@ -1199,9 +1199,9 @@ template <class T> class Processor: public ClockReceiver<Processor<T>> {
 #pragma mark - 16-bit arithmetic
 
 						case MicroOp::ADD16: {
-							memptr_.full = *(uint16_t *)operation->source;
-							uint16_t sourceValue = memptr_.full;
-							uint16_t destinationValue = *(uint16_t *)operation->destination;
+							memptr_.full = *(uint16_t *)operation->destination;
+							uint16_t sourceValue = *(uint16_t *)operation->source;
+							uint16_t destinationValue = memptr_.full;
 							int result = sourceValue + destinationValue;
 							int halfResult = (sourceValue&0xfff) + (destinationValue&0xfff);
 
@@ -1211,12 +1211,13 @@ template <class T> class Processor: public ClockReceiver<Processor<T>> {
 							subtract_flag_ = 0;
 
 							*(uint16_t *)operation->destination = (uint16_t)result;
+							memptr_.full++;
 						} break;
 
 						case MicroOp::ADC16: {
-							memptr_.full = *(uint16_t *)operation->source;
-							uint16_t sourceValue = memptr_.full;
-							uint16_t destinationValue = *(uint16_t *)operation->destination;
+							memptr_.full = *(uint16_t *)operation->destination;
+							uint16_t sourceValue = *(uint16_t *)operation->source;
+							uint16_t destinationValue = memptr_.full;
 							int result = sourceValue + destinationValue + (carry_result_ & Flag::Carry);
 							int halfResult = (sourceValue&0xfff) + (destinationValue&0xfff) + (carry_result_ & Flag::Carry);
 
@@ -1231,12 +1232,13 @@ template <class T> class Processor: public ClockReceiver<Processor<T>> {
 							parity_overflow_result_ = (uint8_t)(overflow >> 13);
 
 							*(uint16_t *)operation->destination = (uint16_t)result;
+							memptr_.full++;
 						} break;
 
 						case MicroOp::SBC16: {
-							memptr_.full = *(uint16_t *)operation->source;
-							uint16_t sourceValue = memptr_.full;
-							uint16_t destinationValue = *(uint16_t *)operation->destination;
+							memptr_.full = *(uint16_t *)operation->destination;
+							uint16_t sourceValue = *(uint16_t *)operation->source;
+							uint16_t destinationValue = memptr_.full;
 							int result = destinationValue - sourceValue - (carry_result_ & Flag::Carry);
 							int halfResult = (destinationValue&0xfff) - (sourceValue&0xfff) - (carry_result_ & Flag::Carry);
 
@@ -1254,6 +1256,7 @@ template <class T> class Processor: public ClockReceiver<Processor<T>> {
 							parity_overflow_result_ = (uint8_t)(overflow >> 13);
 
 							*(uint16_t *)operation->destination = (uint16_t)result;
+							memptr_.full++;
 						} break;
 
 #pragma mark - Conditionals