diff --git a/InstructionSets/ARM/Registers.hpp b/InstructionSets/ARM/Registers.hpp
index c3158b5d2..5c7bba41a 100644
--- a/InstructionSets/ARM/Registers.hpp
+++ b/InstructionSets/ARM/Registers.hpp
@@ -231,7 +231,7 @@ struct Registers {
 		// MARK: - Condition tests.
 
 		/// @returns @c true if @c condition tests as true; @c false otherwise.
-		bool test(Condition condition) {
+		bool test(Condition condition) const {
 			const auto ne = [&]() -> bool {
 				return zero_result_;
 			};
diff --git a/Machines/Acorn/Archimedes/Archimedes.cpp b/Machines/Acorn/Archimedes/Archimedes.cpp
index b44dfecdc..b03138460 100644
--- a/Machines/Acorn/Archimedes/Archimedes.cpp
+++ b/Machines/Acorn/Archimedes/Archimedes.cpp
@@ -549,7 +549,7 @@ class ConcreteMachine:
 
 		uint32_t advance_pipeline(uint32_t pc) {
 			uint32_t instruction = 0;	// Value should never be used; this avoids a spurious GCC warning.
-			const bool did_read = executor_.bus.read(pc, instruction, executor_.registers().mode(), false);
+			const bool did_read = executor_.bus.read(pc, instruction,  executor_.registers().mode() == InstructionSet::ARM::Mode::User);
 			return pipeline_.exchange(
 				did_read ? instruction : Pipeline::SWI,
 				did_read ? Pipeline::SWISubversion::None : Pipeline::SWISubversion::DataAbort);
diff --git a/Machines/Acorn/Archimedes/MemoryController.hpp b/Machines/Acorn/Archimedes/MemoryController.hpp
index 6e91b8ef2..48056e6a6 100644
--- a/Machines/Acorn/Archimedes/MemoryController.hpp
+++ b/Machines/Acorn/Archimedes/MemoryController.hpp
@@ -173,7 +173,7 @@ struct MemoryController {
 	}
 
 	template <typename IntT>
-	bool read(uint32_t address, IntT &source, InstructionSet::ARM::Mode, bool trans) {
+	bool read(uint32_t address, IntT &source, bool trans) {
 		switch (read_zones_[(address >> 21) & 31]) {
 			case Zone::PhysicallyMappedRAM:
 				if(trans) return false;
@@ -212,6 +212,11 @@ struct MemoryController {
 		return true;
 	}
 
+	template <typename IntT>
+	bool read(uint32_t address, IntT &source, InstructionSet::ARM::Mode, bool trans) {
+		return read(address, source, trans);
+	}
+
 	//
 	// Expose various IOC-owned things.
 	//