diff --git a/Machines/Acorn/BBCMicro/Keyboard.hpp b/Machines/Acorn/BBCMicro/Keyboard.hpp
index 6b12ad4c7..b2c888c50 100644
--- a/Machines/Acorn/BBCMicro/Keyboard.hpp
+++ b/Machines/Acorn/BBCMicro/Keyboard.hpp
@@ -49,7 +49,7 @@ enum class BBCKey: uint16_t {
 	//
 	// Break; a key, but not on the keyboard matrix.
 	//
-	Break = 0xfffd,
+	Break = 0xfffc,
 
 	//
 	// Master only keys.
diff --git a/Machines/Acorn/Electron/Keyboard.cpp b/Machines/Acorn/Electron/Keyboard.cpp
index 7c972f3b9..b710c26d9 100644
--- a/Machines/Acorn/Electron/Keyboard.cpp
+++ b/Machines/Acorn/Electron/Keyboard.cpp
@@ -10,7 +10,7 @@
 
 using namespace Electron;
 
-uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
+uint16_t KeyboardMapper::mapped_key_for_key(const Inputs::Keyboard::Key key) const {
 #define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return Electron::Key::dest
 	switch(key) {
 		default: break;
@@ -70,7 +70,7 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 	return MachineTypes::MappedKeyboardMachine::KeyNotMapped;
 }
 
-const uint16_t *CharacterMapper::sequence_for_character(char character) const {
+const uint16_t *CharacterMapper::sequence_for_character(const char character) const {
 #define KEYS(...)	{__VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define SHIFT(...)	{KeyShift, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define CTRL(...)	{KeyControl, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
@@ -148,6 +148,6 @@ const uint16_t *CharacterMapper::sequence_for_character(char character) const {
 	return table_lookup_sequence_for_character(key_sequences, character);
 }
 
-bool CharacterMapper::needs_pause_after_key(uint16_t key) const {
+bool CharacterMapper::needs_pause_after_key(const uint16_t key) const {
 	return !is_modifier(Key(key));
 }
diff --git a/Machines/Acorn/Electron/Keyboard.hpp b/Machines/Acorn/Electron/Keyboard.hpp
index fcb25d042..1b1baf20e 100644
--- a/Machines/Acorn/Electron/Keyboard.hpp
+++ b/Machines/Acorn/Electron/Keyboard.hpp
@@ -32,7 +32,7 @@ enum Key: uint16_t {
 	// Virtual keys.
 	KeyF1			= 0xfff0, KeyF2, KeyF3, KeyF4, KeyF5, KeyF6, KeyF7, KeyF8, KeyF9, KeyF0,
 
-	KeyBreak		= 0xfffd,
+	KeyBreak		= 0xfffc,
 };
 
 constexpr bool is_modifier(const Key key) {
diff --git a/Machines/Commodore/Vic-20/Keyboard.hpp b/Machines/Commodore/Vic-20/Keyboard.hpp
index efdc9b5a1..2d2eca599 100644
--- a/Machines/Commodore/Vic-20/Keyboard.hpp
+++ b/Machines/Commodore/Vic-20/Keyboard.hpp
@@ -44,7 +44,7 @@ enum Key: uint16_t {
 	KeyF8		= 0xfff5,
 
 	// Physical keys not within the usual matrix.
-	KeyRestore	= 0xfffd,
+	KeyRestore	= 0xfffc,
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
diff --git a/Machines/KeyboardMachine.hpp b/Machines/KeyboardMachine.hpp
index 5fc8b37b6..d8944bb52 100644
--- a/Machines/KeyboardMachine.hpp
+++ b/Machines/KeyboardMachine.hpp
@@ -137,6 +137,12 @@ public:
 	*/
 	static constexpr uint16_t KeyNotMapped = 0xfffe;
 
+	/*!
+		Indicates that a key is not mapped (for the keyboard mapper) or that a
+		character cannot be typed (for the character mapper).
+	*/
+	static constexpr uint16_t DelaySlot = 0xfffd;
+
 	/*!
 		Allows individual machines to provide the mapping between host keys
 		as per Inputs::Keyboard and their native scheme.
diff --git a/Machines/Oric/Keyboard.hpp b/Machines/Oric/Keyboard.hpp
index 0468f5a0f..e7173f9ca 100644
--- a/Machines/Oric/Keyboard.hpp
+++ b/Machines/Oric/Keyboard.hpp
@@ -31,8 +31,8 @@ enum Key: uint16_t {
 	KeyEquals		= 0x0700 | 0x80,										KeyReturn		= 0x0700 | 0x20,	KeyRightShift	= 0x0700 | 0x10,
 	KeyForwardSlash	= 0x0700 | 0x08,	Key0			= 0x0700 | 0x04,	KeyL			= 0x0700 | 0x02,	Key8			= 0x0700 | 0x01,
 
-	KeyNMI			= 0xfffd,
-	KeyJasminReset	= 0xfffc,
+	KeyNMI			= 0xfffc,
+	KeyJasminReset	= 0xfffb,
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
diff --git a/Machines/Utility/Typer.cpp b/Machines/Utility/Typer.cpp
index bb1b6e53f..4396530ee 100644
--- a/Machines/Utility/Typer.cpp
+++ b/Machines/Utility/Typer.cpp
@@ -96,7 +96,7 @@ uint16_t Typer::try_type_next_character() {
 		delegate_->clear_all_keys();
 		if(character_mapper_.needs_pause_after_reset_all_keys() ||
 			(string_pointer_ > 0 && string_[string_pointer_ - 1] == string_[string_pointer_])) {
-			return 0xffff;	// Arbitrarily. Anything non-zero will do.
+			return MachineTypes::MappedKeyboardMachine::DelaySlot;
 		}
 		++phase_;
 	}