diff --git a/InstructionSets/68k/Decoder.cpp b/InstructionSets/68k/Decoder.cpp
index d4e037028..367848932 100644
--- a/InstructionSets/68k/Decoder.cpp
+++ b/InstructionSets/68k/Decoder.cpp
@@ -488,7 +488,8 @@ template <uint8_t op, bool validate> Preinstruction Predecoder<model>::validated
 			operation,
 			op1_mode, op1_reg,
 			op2_mode, op2_reg,
-			requires_supervisor<model>(operation));
+			requires_supervisor<model>(operation),
+			size(operation));
 	}
 
 	const auto invalid = invalid_operands<op>();
@@ -499,7 +500,8 @@ template <uint8_t op, bool validate> Preinstruction Predecoder<model>::validated
 			operation,
 			op1_mode, op1_reg,
 			op2_mode, op2_reg,
-			requires_supervisor<model>(operation));
+			requires_supervisor<model>(operation),
+			size(operation));
 }
 
 /// Decodes the fields within an instruction and constructs a `Preinstruction`, given that the operation has already been
diff --git a/InstructionSets/68k/Instruction.hpp b/InstructionSets/68k/Instruction.hpp
index d200bf0ff..3ae2e7006 100644
--- a/InstructionSets/68k/Instruction.hpp
+++ b/InstructionSets/68k/Instruction.hpp
@@ -359,28 +359,30 @@ class Preinstruction {
 			return operands_[index] >> 5;
 		}
 
+		bool requires_supervisor() {
+			return flags_ & 0x80;
+		}
+		DataSize size() {
+			return DataSize(flags_ & 0x7f);
+		}
+
 	private:
 		uint8_t operands_[2] = { uint8_t(AddressingMode::None), uint8_t(AddressingMode::None)};
+		uint8_t flags_ = 0;
 
 	public:
 		Preinstruction(
 			Operation operation,
 			AddressingMode op1_mode,	int op1_reg,
 			AddressingMode op2_mode,	int op2_reg,
-			[[maybe_unused]] bool is_supervisor = false) : operation(operation)
+			bool is_supervisor,
+			DataSize size) : operation(operation)
 		{
 			operands_[0] = uint8_t(op1_mode) | uint8_t(op1_reg << 5);
 			operands_[1] = uint8_t(op2_mode) | uint8_t(op2_reg << 5);
+			flags_ = (is_supervisor ? 0x80 : 0x00) | uint8_t(size);
 		}
 
-		Preinstruction(Operation operation, [[maybe_unused]] bool is_supervisor = false) : operation(operation) {}
-
-		Preinstruction(Operation operation, AddressingMode op1_mode, int op1_reg, [[maybe_unused]] bool is_supervisor = false) : operation(operation) {
-			operands_[0] = uint8_t(op1_mode) | uint8_t(op1_reg << 5);
-		}
-
-		// TODO: record is_supervisor.
-
 		Preinstruction() {}
 };