diff --git a/src/lexer/lexer.c b/src/lexer/lexer.c
index 680fd0d..0cd5f89 100644
--- a/src/lexer/lexer.c
+++ b/src/lexer/lexer.c
@@ -95,44 +95,44 @@ struct lexer {
   dstr_t *error_message;
 };
 
-void stack_push(state_stack_t *stack, lexer_state_t value);
-lexer_state_t stack_pop(state_stack_t *stack);
+INTERNAL void stack_push(state_stack_t *stack, lexer_state_t value);
+INTERNAL lexer_state_t stack_pop(state_stack_t *stack);
 
-void append_to_lex_str(lexer_string_t *str, char input);
-void clear_lex_str(lexer_string_t *str);
-bool strequal(const char *const first, const char *const second);
-bool is_valid_hex_char(const char input);
-bool ishex(const char input);
+INTERNAL void append_to_lex_str(lexer_string_t *str, char input);
+INTERNAL void clear_lex_str(lexer_string_t *str);
+INTERNAL bool strequal(const char *const first, const char *const second);
+INTERNAL bool is_valid_hex_char(const char input);
+INTERNAL bool ishex(const char input);
 
-token_t dstr_to_numerical_token(const dstr_t *str);
-void set_token(token_t *token, u64 line, u64 column, token_type type,
-               token_value_t value);
+INTERNAL token_t dstr_to_numerical_token(const dstr_t *str);
+INTERNAL void set_token(token_t *token, u64 line, u64 column, token_type type,
+                        token_value_t value);
 
-void lexer_state_machine(lexer_t *lexer, char input);
-lexer_state_t handle_lexer_start(lexer_t *lexer, char input);
-lexer_state_t handle_last_collection(char input);
-lexer_state_t handle_collection_end(lexer_t *lexer, char input);
-void handle_input_after_collection_end(lexer_t *lexer, char input);
-lexer_state_t handle_object(lexer_t *lexer, char input);
-lexer_state_t handle_array(lexer_t *lexer, char input);
-lexer_state_t handle_key(lexer_t *lexer, char input);
-lexer_state_t handle_value(lexer_t *lexer, char input);
-lexer_state_t handle_string(lexer_t *lexer, char input);
-lexer_state_t handle_string_end(lexer_t *lexer, char input);
-lexer_state_t handle_escape_sequence(lexer_t *lexer, char input);
-lexer_state_t handle_unicode_sequence(lexer_t *lexer, char input);
-lexer_state_t handle_decimal(lexer_t *lexer, char input);
-lexer_state_t handle_number(lexer_t *lexer, char input);
-lexer_state_t handle_fraction(lexer_t *lexer, char input);
-lexer_state_t handle_exponent(lexer_t *lexer, char input);
-lexer_state_t handle_exp_sign(lexer_t *lexer, char input);
-lexer_state_t handle_power(lexer_t *lexer, char input);
-lexer_state_t handle_number_end(lexer_t *lexer, char input);
-lexer_state_t handle_keyword(char input);
-lexer_state_t handle_true(lexer_t *lexer, char input);
-lexer_state_t handle_false(lexer_t *lexer, char input);
-lexer_state_t handle_null(lexer_t *lexer, char input);
-lexer_state_t handle_keyword_end(lexer_t *lexer, char input);
+INTERNAL void lexer_state_machine(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_lexer_start(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_last_collection(char input);
+INTERNAL lexer_state_t handle_collection_end(lexer_t *lexer, char input);
+INTERNAL void handle_input_after_collection_end(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_object(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_array(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_key(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_value(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_string(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_string_end(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_escape_sequence(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_unicode_sequence(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_decimal(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_number(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_fraction(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_exponent(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_exp_sign(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_power(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_number_end(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_keyword(char input);
+INTERNAL lexer_state_t handle_true(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_false(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_null(lexer_t *lexer, char input);
+INTERNAL lexer_state_t handle_keyword_end(lexer_t *lexer, char input);
 
 void lexer_init(lexer_t **lexer) {
   if (*lexer) {