diff --git a/InstructionSets/x86/Implementation/PerformImplementation.hpp b/InstructionSets/x86/Implementation/PerformImplementation.hpp
index 593980bf0..bd36a79cd 100644
--- a/InstructionSets/x86/Implementation/PerformImplementation.hpp
+++ b/InstructionSets/x86/Implementation/PerformImplementation.hpp
@@ -172,7 +172,7 @@ template <typename IntT> constexpr int bit_size() {
 /// and the result was @c result. All other bits will be clear.
 template <bool is_add, typename IntT>
 IntT overflow(IntT lhs, IntT rhs, IntT result) {
-	const IntT output_changed = result ^ rhs;
+	const IntT output_changed = result ^ lhs;
 	const IntT input_differed = lhs ^ rhs;
 
 	if constexpr (is_add) {
@@ -181,6 +181,8 @@ IntT overflow(IntT lhs, IntT rhs, IntT result) {
 		return top_bit<IntT>() & output_changed & input_differed;
 	}
 }
+// NOTE TO FUTURE SELF: the original 68k `overflow` treats lhs and rhs the other way
+// around, affecting subtractive overflow. Be careful.
 
 //
 // END COPY AND PASTE SECTION.
diff --git a/OSBindings/Mac/Clock SignalTests/8088Tests.mm b/OSBindings/Mac/Clock SignalTests/8088Tests.mm
index 8c0831006..00ab3b4b8 100644
--- a/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
@@ -304,12 +304,12 @@ struct FailedExecution {
 //		@"80.0.json.gz", @"81.0.json.gz", @"83.0.json.gz",
 
 		// SBB
-//		@"18.json.gz",	@"19.json.gz",	@"1A.json.gz",	@"1B.json.gz",	@"1C.json.gz",	@"1D.json.gz",
-//		@"80.3.json.gz", @"81.3.json.gz", @"83.3.json.gz",
+		@"18.json.gz",	@"19.json.gz",	@"1A.json.gz",	@"1B.json.gz",	@"1C.json.gz",	@"1D.json.gz",
+		@"80.3.json.gz", @"81.3.json.gz", @"83.3.json.gz",
 
 		// SUB
-		@"28.json.gz",	//@"29.json.gz",	@"2A.json.gz",	@"2B.json.gz",	@"2C.json.gz",	@"2D.json.gz",
-//		@"80.5.json.gz", @"81.5.json.gz", @"83.5.json.gz",
+		@"28.json.gz",	@"29.json.gz",	@"2A.json.gz",	@"2B.json.gz",	@"2C.json.gz",	@"2D.json.gz",
+		@"80.5.json.gz", @"81.5.json.gz", @"83.5.json.gz",
 
 		// AND
 //		@"20.json.gz",	@"21.json.gz",	@"22.json.gz",	@"23.json.gz",	@"24.json.gz",	@"25.json.gz",