diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 34ce90551..020da0edc 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -846,6 +846,7 @@
 		4BDDBA991EF3451200347E61 /* Z80MachineCycleTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BDDBA981EF3451200347E61 /* Z80MachineCycleTests.swift */; };
 		4BE0A3EE237BB170002AB46F /* ST.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BE0A3EC237BB170002AB46F /* ST.cpp */; };
 		4BE0A3EF237BB170002AB46F /* ST.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BE0A3EC237BB170002AB46F /* ST.cpp */; };
+		4BE211DE253E4E4800435408 /* 65C02_no_Rockwell_test.bin in Resources */ = {isa = PBXBuildFile; fileRef = 4BE211DD253E4E4800435408 /* 65C02_no_Rockwell_test.bin */; };
 		4BE34438238389E10058E78F /* AtariSTVideoTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BE34437238389E10058E78F /* AtariSTVideoTests.mm */; };
 		4BE76CF922641ED400ACD6FA /* QLTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BE76CF822641ED300ACD6FA /* QLTests.mm */; };
 		4BE90FFD22D5864800FB464D /* MacintoshVideoTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BE90FFC22D5864800FB464D /* MacintoshVideoTests.mm */; };
@@ -1768,6 +1769,7 @@
 		4BDDBA981EF3451200347E61 /* Z80MachineCycleTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Z80MachineCycleTests.swift; sourceTree = "<group>"; };
 		4BE0A3EC237BB170002AB46F /* ST.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ST.cpp; sourceTree = "<group>"; };
 		4BE0A3ED237BB170002AB46F /* ST.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = ST.hpp; sourceTree = "<group>"; };
+		4BE211DD253E4E4800435408 /* 65C02_no_Rockwell_test.bin */ = {isa = PBXFileReference; lastKnownFileType = archive.macbinary; name = 65C02_no_Rockwell_test.bin; path = "Klaus Dormann/65C02_no_Rockwell_test.bin"; sourceTree = "<group>"; };
 		4BE3231220532443006EF799 /* Target.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Target.hpp; sourceTree = "<group>"; };
 		4BE32313205327D7006EF799 /* Target.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Target.hpp; sourceTree = "<group>"; };
 		4BE32314205328FF006EF799 /* Target.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Target.hpp; sourceTree = "<group>"; };
@@ -1994,6 +1996,7 @@
 				4B44EBF81DC9898E00A7820C /* BCDTEST_beeb */,
 				4B98A1CD1FFADEC400ADF63B /* MSX ROMs */,
 				4B018B88211930DE002A3937 /* 65C02_extended_opcodes_test.bin */,
+				4BE211DD253E4E4800435408 /* 65C02_no_Rockwell_test.bin */,
 				4B44EBF61DC9883B00A7820C /* 6502_functional_test.bin */,
 				4B44EBF41DC987AE00A7820C /* AllSuiteA.bin */,
 				4B9F11CB22729B3500701480 /* OPCLOGR2.BIN */,
@@ -4230,6 +4233,7 @@
 				4BB299961B587D8400A49093 /* nmi in Resources */,
 				4BB299241B587D8400A49093 /* cia1ta in Resources */,
 				4BB2990E1B587D8400A49093 /* asoix in Resources */,
+				4BE211DE253E4E4800435408 /* 65C02_no_Rockwell_test.bin in Resources */,
 				4BB299F51B587D8400A49093 /* trap9 in Resources */,
 				4BB299C81B587D8400A49093 /* sbcb(eb) in Resources */,
 				4BB299CF1B587D8400A49093 /* sedn in Resources */,
diff --git a/OSBindings/Mac/Clock SignalTests/Klaus Dormann/65C02_no_Rockwell_test.bin b/OSBindings/Mac/Clock SignalTests/Klaus Dormann/65C02_no_Rockwell_test.bin
new file mode 100644
index 000000000..c60b95b8a
Binary files /dev/null and b/OSBindings/Mac/Clock SignalTests/Klaus Dormann/65C02_no_Rockwell_test.bin differ
diff --git a/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift b/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift
index 68c4c1642..0467e280f 100644
--- a/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift	
+++ b/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift	
@@ -118,6 +118,24 @@ class KlausDormannTests: XCTestCase {
 		XCTAssert(error == nil, "Failed with error \(error!)")
 	}
 
+	private func runTest65C02NoRockwell(processor: CSTestMachine6502Processor) {
+		func errorForTrapAddress(_ address: UInt16) -> String? {
+			switch address {
+				case 0x11e0: return nil // success!
+
+				case 0x1474: return "BRK didn't clear the decimal flag"
+				case 0x0e3d: return "TRB set flags incorrectly"
+
+				case 0: return "Didn't find tests"
+				default: return "Unknown error at \(String(format:"%04x", address))"
+			}
+		}
+
+		let destination = runTest(resource: "65C02_no_Rockwell_test", processor: processor)
+		let error = errorForTrapAddress(destination)
+		XCTAssert(error == nil, "Failed with error \(error!)")
+	}
+
 
 	/// Runs Klaus Dormann's 6502 tests.
 	func test6502() {
@@ -134,6 +152,11 @@ class KlausDormannTests: XCTestCase {
 		runTest6502(processor: .processor65816)
 	}
 
+	/// Runs Klaus Dormann's standard 6502 tests on a 65816.
+	func test65816AsNonRockwell65C02() {
+		runTest65C02NoRockwell(processor: .processor65816)
+	}
+
 	/// Runs Klaus Dormann's 65C02 tests.
 	func test65C02() {
 		runTest65C02(processor: .processor65C02)
diff --git a/Processors/65816/Implementation/65816Implementation.hpp b/Processors/65816/Implementation/65816Implementation.hpp
index 39180736c..c8750a6e0 100644
--- a/Processors/65816/Implementation/65816Implementation.hpp
+++ b/Processors/65816/Implementation/65816Implementation.hpp
@@ -444,6 +444,7 @@ template <typename BusHandler, bool uses_ready_line> void Processor<BusHandler,
 					}
 
 					registers_.flags.inverse_interrupt = 0;
+					registers_.flags.decimal = 0;
 				} continue;
 
 				//
diff --git a/Processors/65816/Implementation/65816Storage.cpp b/Processors/65816/Implementation/65816Storage.cpp
index 62981004a..06cff2dc7 100644
--- a/Processors/65816/Implementation/65816Storage.cpp
+++ b/Processors/65816/Implementation/65816Storage.cpp
@@ -775,7 +775,7 @@ ProcessorStorage::ProcessorStorage() {
 	/* 0x11 ORA (d), y */		op(direct_indirect_indexed, ORA);
 	/* 0x12 ORA (d) */			op(direct_indirect, ORA);
 	/* 0x13 ORA (d, s), y */	op(stack_relative_indexed_indirect, ORA);
-	/* 0x14 TRB d */			op(absolute_rmw, TRB);
+	/* 0x14 TRB d */			op(direct_rmw, TRB);
 	/* 0x15 ORA d, x */			op(direct_x, ORA);
 	/* 0x16 ASL d, x */			op(direct_x_rmw, ASL);
 	/* 0x17 ORA [d], y */		op(direct_indirect_indexed_long, ORA);