diff --git a/Machines/Utility/Typer.cpp b/Machines/Utility/Typer.cpp
index 4470f97c2..9706d85bf 100644
--- a/Machines/Utility/Typer.cpp
+++ b/Machines/Utility/Typer.cpp
@@ -134,7 +134,7 @@ bool Typer::type_next_character() {
 
 // MARK: - Character mapper
 
-uint16_t *CharacterMapper::table_lookup_sequence_for_character(KeySequence *sequences, std::size_t length, char character) const {
+const uint16_t *CharacterMapper::table_lookup_sequence_for_character(const KeySequence *sequences, std::size_t length, char character) const {
 	std::size_t ucharacter = size_t((unsigned char)character);
 	if(ucharacter >= (length / sizeof(KeySequence))) return nullptr;
 	if(sequences[ucharacter][0] == MachineTypes::MappedKeyboardMachine::KeyNotMapped) return nullptr;
diff --git a/Machines/Utility/Typer.hpp b/Machines/Utility/Typer.hpp
index d6bdc80f7..0e0a15b3a 100644
--- a/Machines/Utility/Typer.hpp
+++ b/Machines/Utility/Typer.hpp
@@ -48,7 +48,7 @@ class CharacterMapper {
 			with @c length entries, returns the sequence for character @c character if it exists; otherwise
 			returns @c nullptr.
 		*/
-		uint16_t *table_lookup_sequence_for_character(KeySequence *sequences, std::size_t length, char character) const;
+		const uint16_t *table_lookup_sequence_for_character(const KeySequence *sequences, std::size_t length, char character) const;
 };
 
 /*!