diff --git a/src/arch/avr/i2c.c b/src/arch/avr/i2c.c
index 2cb1161..d22752e 100644
--- a/src/arch/avr/i2c.c
+++ b/src/arch/avr/i2c.c
@@ -10,7 +10,7 @@
 
 #define TIMEOUT (F_CPU/1000)
 
-int i2c_start(struct I2C * i2c, uint8_t addr, bool read) {
+int16_t i2c_start(struct I2C * i2c, uint8_t addr, bool read) {
     uint32_t count;
 
     // reset TWI control register
@@ -46,8 +46,8 @@ void i2c_stop(struct I2C * i2c) {
     TWCR = BIT(TWINT) | BIT(TWEN) | BIT(TWSTO);
 }
 
-int i2c_write(struct I2C * i2c, uint8_t * data, int length) {
-    int i;
+int16_t i2c_write(struct I2C * i2c, uint8_t * data, int16_t length) {
+    int16_t i;
     for (i = 0; i < length; i++) {
         // load data into data register
         TWDR = data[i];
@@ -65,8 +65,8 @@ int i2c_write(struct I2C * i2c, uint8_t * data, int length) {
     return i;
 }
 
-int i2c_read(struct I2C * i2c, uint8_t * data, int length) {
-    int i;
+int16_t i2c_read(struct I2C * i2c, uint8_t * data, int16_t length) {
+    int16_t i;
     for (i = 0; i < length; i++) {
         if ((i + 1) < length) {
             // start TWI module and acknowledge data after reception
diff --git a/src/arch/avr/include/arch/uart.h b/src/arch/avr/include/arch/uart.h
index 80e7dfd..2e63e72 100644
--- a/src/arch/avr/include/arch/uart.h
+++ b/src/arch/avr/include/arch/uart.h
@@ -19,18 +19,18 @@ struct Uart {
     uint8_t c_init;
 };
 
-void uart_init(struct Uart * uart, unsigned long baud);
+void uart_init(struct Uart * uart, uint32_t baud);
 
-int uart_count();
-struct Uart * uart_new(int num);
+int16_t uart_count();
+struct Uart * uart_new(int16_t num);
 
-unsigned char uart_can_read(struct Uart * uart);
-unsigned char uart_can_write(struct Uart * uart);
+uint8_t uart_can_read(struct Uart * uart);
+uint8_t uart_can_write(struct Uart * uart);
 
-unsigned char uart_read(struct Uart * uart);
-void uart_write(struct Uart * uart, unsigned char data);
+uint8_t uart_read(struct Uart * uart);
+void uart_write(struct Uart * uart, uint8_t data);
 
 extern struct Uart * uart_stdio;
-void uart_stdio_init(int num, unsigned long baud);
+void uart_stdio_init(int16_t num, uint32_t baud);
 
 #endif // _ARCH_UART_H
diff --git a/src/arch/avr/uart.c b/src/arch/avr/uart.c
index c012a72..589827b 100644
--- a/src/arch/avr/uart.c
+++ b/src/arch/avr/uart.c
@@ -40,11 +40,11 @@
     #error "Could not find UART definitions"
 #endif
 
-int uart_count() {
+int16_t uart_count() {
     return sizeof(UARTS)/sizeof(struct Uart);
 }
 
-struct Uart * uart_new(int num) {
+struct Uart * uart_new(int16_t num) {
     if (num < uart_count()) {
         return &UARTS[num];
     } else {
@@ -52,8 +52,8 @@ struct Uart * uart_new(int num) {
     }
 }
 
-void uart_init(struct Uart * uart, unsigned long baud) {
-    unsigned long baud_prescale = (F_CPU / (baud * 16UL)) - 1;
+void uart_init(struct Uart * uart, uint32_t baud) {
+    uint32_t baud_prescale = (F_CPU / (baud * 16UL)) - 1;
     *(uart->baud_h) = (uint8_t)(baud_prescale>>8);
     *(uart->baud_l) = (uint8_t)(baud_prescale);
     *(uart->a) = uart->a_init;
@@ -61,38 +61,38 @@ void uart_init(struct Uart * uart, unsigned long baud) {
     *(uart->c) = uart->c_init;
 }
 
-unsigned char uart_can_read(struct Uart * uart) {
+uint8_t uart_can_read(struct Uart * uart) {
     return (*(uart->a)) & uart->a_read;
 }
 
-unsigned char uart_read(struct Uart * uart) {
+uint8_t uart_read(struct Uart * uart) {
     while (!uart_can_read(uart)) ;
     return *(uart->data);
 }
 
-unsigned char uart_can_write(struct Uart * uart) {
+uint8_t uart_can_write(struct Uart * uart) {
     return (*(uart->a)) & uart->a_write;
 }
 
-void uart_write(struct Uart * uart, unsigned char data) {
+void uart_write(struct Uart * uart, uint8_t data) {
     while (!uart_can_write(uart)) ;
     *(uart->data) = data;
 }
 
 struct Uart * uart_stdio = NULL;
 
-int uart_stdio_get(FILE * stream) {
-    return (int)uart_read(uart_stdio);
+int16_t uart_stdio_get(FILE * stream) {
+    return (int16_t)uart_read(uart_stdio);
 }
 
-int uart_stdio_put(char data, FILE * stream) {
-    uart_write(uart_stdio, (unsigned char)data);
+int16_t uart_stdio_put(char data, FILE * stream) {
+    uart_write(uart_stdio, (uint8_t)data);
     return 0;
 }
 
 FILE uart_stdio_file = FDEV_SETUP_STREAM(uart_stdio_put, uart_stdio_get, _FDEV_SETUP_RW);
 
-void uart_stdio_init(int num, unsigned long baud) {
+void uart_stdio_init(int16_t num, uint32_t baud) {
     struct Uart * uart = uart_new(num);
     if(uart != NULL) {
         uart_init(uart, baud);
diff --git a/src/board/arduino/mega2560/battery.c b/src/board/arduino/mega2560/battery.c
index 5f6ce3d..183288c 100644
--- a/src/board/arduino/mega2560/battery.c
+++ b/src/board/arduino/mega2560/battery.c
@@ -4,17 +4,17 @@
 
 #include <common/i2c.h>
 
-int smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
+int16_t smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
     return i2c_get(NULL, address, command, (uint8_t *)data, 2);
 }
 
-int smbus_write(uint8_t address, uint8_t command, uint16_t data) {
+int16_t smbus_write(uint8_t address, uint8_t command, uint16_t data) {
     return i2c_set(NULL, address, command, (uint8_t *)&data, 2);
 }
 
 void battery_debug(void) {
     uint16_t data = 0;
-    int res = 0;
+    int16_t res = 0;
 
     #define command(N, A, V) { \
         printf(#N ": "); \
diff --git a/src/board/arduino/mega2560/i2c.c b/src/board/arduino/mega2560/i2c.c
index 3c056a3..cb58e91 100644
--- a/src/board/arduino/mega2560/i2c.c
+++ b/src/board/arduino/mega2560/i2c.c
@@ -5,7 +5,7 @@
 #include <board/cpu.h>
 #include <board/i2c.h>
 
-void i2c_init(unsigned long baud) {
+void i2c_init(uint32_t baud) {
     TWAR = 0;
     TWBR = (uint8_t)(((F_CPU / baud) - 16 ) / 2);
     TWCR = 0;
diff --git a/src/board/arduino/mega2560/include/board/i2c.h b/src/board/arduino/mega2560/include/board/i2c.h
index 735558f..dbec82a 100644
--- a/src/board/arduino/mega2560/include/board/i2c.h
+++ b/src/board/arduino/mega2560/include/board/i2c.h
@@ -3,6 +3,6 @@
 #ifndef _BOARD_I2C_H
 #define _BOARD_I2C_H
 
-void i2c_init(unsigned long baud);
+void i2c_init(uint32_t baud);
 
 #endif // _BOARD_I2C_H
diff --git a/src/board/arduino/mega2560/main.c b/src/board/arduino/mega2560/main.c
index a8067b4..895567d 100644
--- a/src/board/arduino/mega2560/main.c
+++ b/src/board/arduino/mega2560/main.c
@@ -12,7 +12,7 @@ void init(void) {
 struct Gpio LED = GPIO(B, 7);
 
 //TODO: .h file
-void parallel_main(void);
+int parallel_main(void);
 
 int main(void) {
     init();
diff --git a/src/board/arduino/mega2560/parallel.c b/src/board/arduino/mega2560/parallel.c
index 5b61c1a..eeb4d51 100644
--- a/src/board/arduino/mega2560/parallel.c
+++ b/src/board/arduino/mega2560/parallel.c
@@ -213,7 +213,7 @@ void parallel_write_data(struct Parallel * port, uint8_t byte) {
 }
 
 //TODO: timeout
-int parallel_transaction(struct Parallel * port, uint8_t * data, int length, bool read, bool addr) {
+int16_t parallel_transaction(struct Parallel * port, uint8_t * data, int16_t length, bool read, bool addr) {
     if (!read) {
         // Set write line low
         gpio_set(port->write_n, false);
@@ -222,7 +222,7 @@ int parallel_transaction(struct Parallel * port, uint8_t * data, int length, boo
         parallel_data_forward(port);
     }
 
-    int i;
+    int16_t i;
     uint8_t byte = 0;
     for (i = 0; i < length; i++) {
         // Wait for peripheral to indicate it's ready for next cycle
@@ -333,8 +333,8 @@ static uint8_t SPI_ENABLE = 0xFE;
 static uint8_t SPI_DATA = 0xFD;
 
 // Disable chip
-int parallel_spi_reset(struct Parallel *port) {
-    int res;
+int16_t parallel_spi_reset(struct Parallel *port) {
+    int16_t res;
 
     res = parallel_set_address(port, &ADDRESS_INDAR1, 1);
     if (res < 0) return res;
@@ -349,8 +349,8 @@ int parallel_spi_reset(struct Parallel *port) {
 }
 
 // Enable chip and read or write data
-int parallel_spi_transaction(struct Parallel *port, uint8_t * data, int length, bool read) {
-    int res;
+int16_t parallel_spi_transaction(struct Parallel *port, uint8_t * data, int16_t length, bool read) {
+    int16_t res;
 
     res = parallel_set_address(port, &ADDRESS_INDAR1, 1);
     if (res < 0) return res;
@@ -368,10 +368,10 @@ int parallel_spi_transaction(struct Parallel *port, uint8_t * data, int length,
 #define parallel_spi_write(P, D, L) parallel_spi_transaction(P, D, L, false)
 
 // "Hardware" accelerated SPI programming, requires ECINDARs to be set
-int parallel_spi_program(struct Parallel * port, uint8_t * data, int length, bool initialized) {
+int16_t parallel_spi_program(struct Parallel * port, uint8_t * data, int16_t length, bool initialized) {
     static uint8_t aai[6] = { 0xAD, 0, 0, 0, 0, 0 };
-    int res;
-    int i;
+    int16_t res;
+    int16_t i;
     uint8_t status;
 
     for(i = 0; (i + 1) < length; i+=2) {
@@ -420,13 +420,13 @@ int parallel_spi_program(struct Parallel * port, uint8_t * data, int length, boo
     return i;
 }
 
-int serial_transaction(uint8_t * data, int length, bool read) {
-    int i;
+int16_t serial_transaction(uint8_t * data, int16_t length, bool read) {
+    int16_t i;
     for (i = 0; i < length; i++) {
         if (read) {
             data[i] = (uint8_t)uart_read(uart_stdio);
         } else {
-            uart_write(uart_stdio, (unsigned char)data[i]);
+            uart_write(uart_stdio, (uint8_t)data[i]);
         }
     }
 
@@ -437,20 +437,20 @@ int serial_transaction(uint8_t * data, int length, bool read) {
 #define serial_write(D, L) serial_transaction(D, L, false)
 
 int parallel_main(void) {
-    int res = 0;
+    int16_t res = 0;
 
     struct Parallel * port = &PORT;
     parallel_state(port, PARALLEL_STATE_HIZ);
 
     static uint8_t data[128];
     char command;
-    int length;
-    int i;
+    int16_t length;
+    int16_t i;
     uint8_t address;
     bool set_address = false;
     bool program_aai = false;
 
-    unsigned char console_msg[] = "Entering console mode\n";
+    uint8_t console_msg[] = "Entering console mode\n";
 
     for (;;) {
         // Read command and length
@@ -471,7 +471,7 @@ int parallel_main(void) {
         }
 
         // Length is received data + 1
-        length = ((int)data[1]) + 1;
+        length = ((int16_t)data[1]) + 1;
         // Truncate length to size of data
         if (length > sizeof(data)) length = sizeof(data);
 
diff --git a/src/board/arduino/uno/battery.c b/src/board/arduino/uno/battery.c
index 5f6ce3d..183288c 100644
--- a/src/board/arduino/uno/battery.c
+++ b/src/board/arduino/uno/battery.c
@@ -4,17 +4,17 @@
 
 #include <common/i2c.h>
 
-int smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
+int16_t smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
     return i2c_get(NULL, address, command, (uint8_t *)data, 2);
 }
 
-int smbus_write(uint8_t address, uint8_t command, uint16_t data) {
+int16_t smbus_write(uint8_t address, uint8_t command, uint16_t data) {
     return i2c_set(NULL, address, command, (uint8_t *)&data, 2);
 }
 
 void battery_debug(void) {
     uint16_t data = 0;
-    int res = 0;
+    int16_t res = 0;
 
     #define command(N, A, V) { \
         printf(#N ": "); \
diff --git a/src/board/arduino/uno/i2c.c b/src/board/arduino/uno/i2c.c
index 3c056a3..cb58e91 100644
--- a/src/board/arduino/uno/i2c.c
+++ b/src/board/arduino/uno/i2c.c
@@ -5,7 +5,7 @@
 #include <board/cpu.h>
 #include <board/i2c.h>
 
-void i2c_init(unsigned long baud) {
+void i2c_init(uint32_t baud) {
     TWAR = 0;
     TWBR = (uint8_t)(((F_CPU / baud) - 16 ) / 2);
     TWCR = 0;
diff --git a/src/board/arduino/uno/include/board/i2c.h b/src/board/arduino/uno/include/board/i2c.h
index 735558f..dbec82a 100644
--- a/src/board/arduino/uno/include/board/i2c.h
+++ b/src/board/arduino/uno/include/board/i2c.h
@@ -3,6 +3,6 @@
 #ifndef _BOARD_I2C_H
 #define _BOARD_I2C_H
 
-void i2c_init(unsigned long baud);
+void i2c_init(uint32_t baud);
 
 #endif // _BOARD_I2C_H
diff --git a/src/board/arduino/uno/main.c b/src/board/arduino/uno/main.c
index 5e90797..ea529af 100644
--- a/src/board/arduino/uno/main.c
+++ b/src/board/arduino/uno/main.c
@@ -12,7 +12,7 @@ void init(void) {
 struct Gpio LED = GPIO(B, 5);
 
 //TODO: .h file
-void parallel_main(void);
+int parallel_main(void);
 
 int main(void) {
     init();
diff --git a/src/board/arduino/uno/parallel.c b/src/board/arduino/uno/parallel.c
index 109be1a..cd7b06a 100644
--- a/src/board/arduino/uno/parallel.c
+++ b/src/board/arduino/uno/parallel.c
@@ -162,7 +162,7 @@ void parallel_write_data(struct Parallel * port, uint8_t byte) {
 }
 
 //TODO: timeout
-int parallel_transaction(struct Parallel * port, uint8_t * data, int length, bool read, bool addr) {
+int16_t parallel_transaction(struct Parallel * port, uint8_t * data, int16_t length, bool read, bool addr) {
     if (!read) {
         // Set write line low
         gpio_set(port->write_n, false);
@@ -171,7 +171,7 @@ int parallel_transaction(struct Parallel * port, uint8_t * data, int length, boo
         parallel_data_forward(port);
     }
 
-    int i;
+    int16_t i;
     uint8_t byte = 0;
     for (i = 0; i < length; i++) {
         // Wait for peripheral to indicate it's ready for next cycle
@@ -278,8 +278,8 @@ static uint8_t SPI_ENABLE = 0xFE;
 static uint8_t SPI_DATA = 0xFD;
 
 // Disable chip
-int parallel_spi_reset(struct Parallel *port) {
-    int res;
+int16_t parallel_spi_reset(struct Parallel *port) {
+    int16_t res;
 
     res = parallel_set_address(port, &ADDRESS_INDAR1, 1);
     if (res < 0) return res;
@@ -294,8 +294,8 @@ int parallel_spi_reset(struct Parallel *port) {
 }
 
 // Enable chip and read or write data
-int parallel_spi_transaction(struct Parallel *port, uint8_t * data, int length, bool read) {
-    int res;
+int16_t parallel_spi_transaction(struct Parallel *port, uint8_t * data, int16_t length, bool read) {
+    int16_t res;
 
     res = parallel_set_address(port, &ADDRESS_INDAR1, 1);
     if (res < 0) return res;
@@ -313,10 +313,10 @@ int parallel_spi_transaction(struct Parallel *port, uint8_t * data, int length,
 #define parallel_spi_write(P, D, L) parallel_spi_transaction(P, D, L, false)
 
 // "Hardware" accelerated SPI programming, requires ECINDARs to be set
-int parallel_spi_program(struct Parallel * port, uint8_t * data, int length, bool initialized) {
+int16_t parallel_spi_program(struct Parallel * port, uint8_t * data, int16_t length, bool initialized) {
     static uint8_t aai[6] = { 0xAD, 0, 0, 0, 0, 0 };
-    int res;
-    int i;
+    int16_t res;
+    int16_t i;
     uint8_t status;
 
     for(i = 0; (i + 1) < length; i+=2) {
@@ -365,13 +365,13 @@ int parallel_spi_program(struct Parallel * port, uint8_t * data, int length, boo
     return i;
 }
 
-int serial_transaction(uint8_t * data, int length, bool read) {
-    int i;
+int16_t serial_transaction(uint8_t * data, int16_t length, bool read) {
+    int16_t i;
     for (i = 0; i < length; i++) {
         if (read) {
             data[i] = (uint8_t)uart_read(uart_stdio);
         } else {
-            uart_write(uart_stdio, (unsigned char)data[i]);
+            uart_write(uart_stdio, (uint8_t)data[i]);
         }
     }
 
@@ -381,21 +381,21 @@ int serial_transaction(uint8_t * data, int length, bool read) {
 #define serial_read(D, L) serial_transaction(D, L, true)
 #define serial_write(D, L) serial_transaction(D, L, false)
 
-int parallel_main(void) {
-    int res = 0;
+int16_t parallel_main(void) {
+    int16_t res = 0;
 
     struct Parallel * port = &PORT;
     parallel_reset(port, true);
 
     static uint8_t data[128];
     char command;
-    int length;
-    int i;
+    int16_t length;
+    int16_t i;
     uint8_t address;
     bool set_address = false;
     bool program_aai = false;
 
-    unsigned char console_msg[] = "Entering console mode\n";
+    uint8_t console_msg[] = "Entering console mode\n";
 
     for (;;) {
         // Read command and length
@@ -416,7 +416,7 @@ int parallel_main(void) {
         }
 
         // Length is received data + 1
-        length = ((int)data[1]) + 1;
+        length = ((int16_t)data[1]) + 1;
         // Truncate length to size of data
         if (length > sizeof(data)) length = sizeof(data);
 
diff --git a/src/board/system76/common/battery.c b/src/board/system76/common/battery.c
index 5042d60..662b2d6 100644
--- a/src/board/system76/common/battery.c
+++ b/src/board/system76/common/battery.c
@@ -49,7 +49,7 @@ bool battery_set_end_threshold(uint8_t value) {
 /**
  * Configure the charger based on charging threshold values.
  */
-int battery_charger_configure(void) {
+int16_t battery_charger_configure(void) {
     static bool should_charge = true;
 
     if (battery_get_end_threshold() == BATTERY_END_DEFAULT) {
@@ -85,7 +85,7 @@ uint16_t battery_design_capacity = 0;
 uint16_t battery_design_voltage = 0;
 
 void battery_event(void) {
-    int res = 0;
+    int16_t res = 0;
 
     #define command(N, V) { \
         res = smbus_read(BATTERY_ADDRESS, V, &N); \
diff --git a/src/board/system76/common/charger/bq24780s.c b/src/board/system76/common/charger/bq24780s.c
index bb2e62b..3f1676d 100644
--- a/src/board/system76/common/charger/bq24780s.c
+++ b/src/board/system76/common/charger/bq24780s.c
@@ -21,8 +21,8 @@
 // XXX: Assumption: ac_last is initialized high.
 static bool charger_enabled = false;
 
-int battery_charger_disable(void) {
-    int res = 0;
+int16_t battery_charger_disable(void) {
+    int16_t res = 0;
 
     if (!charger_enabled) return 0;
 
@@ -53,8 +53,8 @@ int battery_charger_disable(void) {
     return 0;
 }
 
-int battery_charger_enable(void) {
-    int res = 0;
+int16_t battery_charger_enable(void) {
+    int16_t res = 0;
 
     if (charger_enabled) return 0;
 
@@ -93,7 +93,7 @@ void battery_charger_event(void) {
 
 void battery_debug(void) {
     uint16_t data = 0;
-    int res = 0;
+    int16_t res = 0;
 
     #define command(N, A, V) { \
         DEBUG("  " #N ": "); \
diff --git a/src/board/system76/common/charger/oz26786.c b/src/board/system76/common/charger/oz26786.c
index 5792ca4..a82fa87 100644
--- a/src/board/system76/common/charger/oz26786.c
+++ b/src/board/system76/common/charger/oz26786.c
@@ -20,8 +20,8 @@
 // XXX: Assumption: ac_last is initialized high.
 static bool charger_enabled = false;
 
-int battery_charger_disable(void) {
-    int res = 0;
+int16_t battery_charger_disable(void) {
+    int16_t res = 0;
 
     if (!charger_enabled) return 0;
 
@@ -61,8 +61,8 @@ int battery_charger_disable(void) {
     return 0;
 }
 
-int battery_charger_enable(void) {
-    int res = 0;
+int16_t battery_charger_enable(void) {
+    int16_t res = 0;
 
     if (charger_enabled) return 0;
 
@@ -112,7 +112,7 @@ void battery_charger_event(void) {
 
 void battery_debug(void) {
     uint16_t data = 0;
-    int res = 0;
+    int16_t res = 0;
 
     #define command(N, A, V) { \
         DEBUG("  " #N ": "); \
diff --git a/src/board/system76/common/dgpu.c b/src/board/system76/common/dgpu.c
index 815723a..ce2c04b 100644
--- a/src/board/system76/common/dgpu.c
+++ b/src/board/system76/common/dgpu.c
@@ -66,7 +66,7 @@ uint8_t dgpu_get_fan_duty(void) {
     if (power_state == POWER_STATE_S0 && gpio_get(&DGPU_PWR_EN) && !gpio_get(&GC6_FB_EN)) {
         // Use I2CS if in S0 state
         int8_t rlts;
-        int res = i2c_get(&I2C_DGPU, 0x4F, 0x00, &rlts, 1);
+        int16_t res = i2c_get(&I2C_DGPU, 0x4F, 0x00, &rlts, 1);
         if (res == 1) {
             dgpu_temp = (int16_t)rlts;
             duty = fan_duty(&FAN, dgpu_temp);
diff --git a/src/board/system76/common/fan.c b/src/board/system76/common/fan.c
index 116ab6d..48a065f 100644
--- a/src/board/system76/common/fan.c
+++ b/src/board/system76/common/fan.c
@@ -26,7 +26,7 @@ void fan_reset(void) {
 // Get duty cycle based on temperature, adapted from
 // https://github.com/pop-os/system76-power/blob/master/src/fan.rs
 uint8_t fan_duty(const struct Fan * fan, int16_t temp) __reentrant {
-    for (int i = 0; i < fan->points_size; i++) {
+    for (int16_t i = 0; i < fan->points_size; i++) {
         const struct FanPoint * cur = &fan->points[i];
 
         // If exactly the current temp, return the current duty
@@ -86,7 +86,7 @@ void fan_duty_set(uint8_t peci_fan_duty, uint8_t dgpu_fan_duty) __reentrant {
 uint8_t fan_heatup(const struct Fan * fan, uint8_t duty) __reentrant {
     uint8_t lowest = duty;
 
-    int i;
+    int16_t i;
     for (i = 0; (i + 1) < fan->heatup_size; i++) {
         uint8_t value = fan->heatup[i + 1];
         if (value < lowest) {
@@ -102,7 +102,7 @@ uint8_t fan_heatup(const struct Fan * fan, uint8_t duty) __reentrant {
 uint8_t fan_cooldown(const struct Fan * fan, uint8_t duty) __reentrant {
     uint8_t highest = duty;
 
-    int i;
+    int16_t i;
     for (i = 0; (i + 1) < fan->cooldown_size; i++) {
         uint8_t value = fan->cooldown[i + 1];
         if (value > highest) {
diff --git a/src/board/system76/common/include/board/battery.h b/src/board/system76/common/include/board/battery.h
index 6921388..7316d5d 100644
--- a/src/board/system76/common/include/board/battery.h
+++ b/src/board/system76/common/include/board/battery.h
@@ -34,13 +34,13 @@ bool battery_set_start_threshold(uint8_t value);
 uint8_t battery_get_end_threshold(void);
 bool battery_set_end_threshold(uint8_t value);
 
-int battery_charger_configure(void);
+int16_t battery_charger_configure(void);
 void battery_event(void);
 void battery_reset(void);
 
 // Defined by charger/*.c
-int battery_charger_disable(void);
-int battery_charger_enable(void);
+int16_t battery_charger_disable(void);
+int16_t battery_charger_enable(void);
 void battery_charger_event(void);
 void battery_debug(void);
 
diff --git a/src/board/system76/common/include/board/parallel.h b/src/board/system76/common/include/board/parallel.h
index e117dba..530def7 100644
--- a/src/board/system76/common/include/board/parallel.h
+++ b/src/board/system76/common/include/board/parallel.h
@@ -8,6 +8,6 @@
 
 extern bool parallel_debug;
 bool parallel_init(void);
-int parallel_write(uint8_t * data, int length);
+int16_t parallel_write(uint8_t * data, int16_t length);
 
 #endif // _BOARD_PARALLEL_H
diff --git a/src/board/system76/common/include/board/peci.h b/src/board/system76/common/include/board/peci.h
index 9e55753..7d6fb9f 100644
--- a/src/board/system76/common/include/board/peci.h
+++ b/src/board/system76/common/include/board/peci.h
@@ -9,7 +9,7 @@ extern bool peci_on;
 extern int16_t peci_temp;
 
 void peci_init(void);
-int peci_wr_pkg_config(uint8_t index, uint16_t param, uint32_t data);
+int16_t peci_wr_pkg_config(uint8_t index, uint16_t param, uint32_t data);
 uint8_t peci_get_fan_duty(void);
 
 #endif // _BOARD_PECI_H
diff --git a/src/board/system76/common/include/board/smbus.h b/src/board/system76/common/include/board/smbus.h
index a3f9512..60220ba 100644
--- a/src/board/system76/common/include/board/smbus.h
+++ b/src/board/system76/common/include/board/smbus.h
@@ -6,7 +6,7 @@
 #include <ec/smbus.h>
 
 void smbus_init(void);
-int smbus_read(uint8_t address, uint8_t command, uint16_t * data);
-int smbus_write(uint8_t address, uint8_t command, uint16_t data);
+int16_t smbus_read(uint8_t address, uint8_t command, uint16_t * data);
+int16_t smbus_write(uint8_t address, uint8_t command, uint16_t data);
 
 #endif // _BOARD_SMBUS_H
diff --git a/src/board/system76/common/include/board/smfi.h b/src/board/system76/common/include/board/smfi.h
index 8d5d32b..56b4a11 100644
--- a/src/board/system76/common/include/board/smfi.h
+++ b/src/board/system76/common/include/board/smfi.h
@@ -3,9 +3,11 @@
 #ifndef _BOARD_SMFI_H
 #define _BOARD_SMFI_H
 
+#include <stdint.h>
+
 void smfi_init(void);
 void smfi_watchdog(void);
 void smfi_event(void);
-void smfi_debug(unsigned char byte);
+void smfi_debug(uint8_t byte);
 
 #endif // _BOARD_SMFI_H
diff --git a/src/board/system76/common/kbled.c b/src/board/system76/common/kbled.c
index 7f7fb7e..4328542 100644
--- a/src/board/system76/common/kbled.c
+++ b/src/board/system76/common/kbled.c
@@ -3,7 +3,7 @@
 #include <board/kbled.h>
 #include <common/macro.h>
 
-static int LEVEL_I = 1;
+static int16_t LEVEL_I = 1;
 static const uint8_t __code LEVELS[] = {
     48,
     72,
@@ -13,7 +13,7 @@ static const uint8_t __code LEVELS[] = {
     255
 };
 
-static int COLOR_I = 0;
+static int16_t COLOR_I = 0;
 static const uint32_t __code COLORS[] = {
     0xFFFFFF,
     0x0000FF,
diff --git a/src/board/system76/common/kbled/bonw14.c b/src/board/system76/common/kbled/bonw14.c
index 802e165..1f31f4f 100644
--- a/src/board/system76/common/kbled/bonw14.c
+++ b/src/board/system76/common/kbled/bonw14.c
@@ -15,7 +15,7 @@ void kbled_init(void) {
 
 void kbled_reset(void) {
     uint8_t value = 0xE4;
-    int res = i2c_set(&I2C_DGPU, 0x2D, 0xA0, &value, 1);
+    int16_t res = i2c_set(&I2C_DGPU, 0x2D, 0xA0, &value, 1);
     DEBUG("kbled_reset 0x2D: %d\n", res);
 
     //value = 0xC4;
diff --git a/src/board/system76/common/kbscan.c b/src/board/system76/common/kbscan.c
index 7d3b3bf..780be1b 100644
--- a/src/board/system76/common/kbscan.c
+++ b/src/board/system76/common/kbscan.c
@@ -30,11 +30,11 @@ uint8_t kbscan_matrix[KM_OUT] = { 0 };
 
 uint8_t sci_extra = 0;
 
-static inline bool matrix_position_is_esc(int row, int col) {
+static inline bool matrix_position_is_esc(int16_t row, int16_t col) {
     return (row == MATRIX_ESC_OUTPUT) && (col == MATRIX_ESC_INPUT);
 }
 
-static inline bool matrix_position_is_fn(int row, int col) {
+static inline bool matrix_position_is_fn(int16_t row, int16_t col) {
     return (row == MATRIX_FN_OUTPUT) && (col == MATRIX_FN_INPUT);
 }
 
@@ -60,7 +60,7 @@ void kbscan_init(void) {
 // Debounce time in milliseconds
 #define DEBOUNCE_DELAY 15
 
-static uint8_t kbscan_get_row(int i) {
+static uint8_t kbscan_get_row(int16_t i) {
     // Report all keys as released when lid is closed
     if (!lid_state) {
         return 0;
@@ -118,7 +118,7 @@ static uint8_t kbscan_get_row(int i) {
 }
 
 #if KM_NKEY
-static bool kbscan_has_ghost_in_row(int row, uint8_t rowdata) {
+static bool kbscan_has_ghost_in_row(int16_t row, uint8_t rowdata) {
     // Use arguments
     row = row;
     rowdata = rowdata;
@@ -129,7 +129,7 @@ static inline bool popcount_more_than_one(uint8_t rowdata) {
     return rowdata & (rowdata - 1);
 }
 
-static uint8_t kbscan_get_real_keys(int row, uint8_t rowdata) {
+static uint8_t kbscan_get_real_keys(int16_t row, uint8_t rowdata) {
     // Remove any "active" blanks from the matrix.
     uint8_t realdata = 0;
     for (uint8_t col = 0; col < KM_IN; col++) {
@@ -143,7 +143,7 @@ static uint8_t kbscan_get_real_keys(int row, uint8_t rowdata) {
     return realdata;
 }
 
-static bool kbscan_has_ghost_in_row(int row, uint8_t rowdata) {
+static bool kbscan_has_ghost_in_row(int16_t row, uint8_t rowdata) {
     rowdata = kbscan_get_real_keys(row, rowdata);
 
     // No ghosts exist when  less than 2 keys in the row are active.
@@ -152,7 +152,7 @@ static bool kbscan_has_ghost_in_row(int row, uint8_t rowdata) {
     }
 
     // Check against other rows to see if more than one column matches.
-    for (int i = 0; i < KM_OUT; i++) {
+    for (int16_t i = 0; i < KM_OUT; i++) {
         uint8_t otherrow = kbscan_get_real_keys(i, kbscan_get_row(i));
         if (i != row && popcount_more_than_one(otherrow & rowdata)) {
             return true;
@@ -315,7 +315,7 @@ void kbscan_event(void) {
         }
     }
 
-    int i;
+    int16_t i;
     for (i = 0; i < KM_OUT; i++) {
         uint8_t new = kbscan_get_row(i);
         uint8_t last = kbscan_matrix[i];
@@ -331,7 +331,7 @@ void kbscan_event(void) {
             }
 
             // A key was pressed or released
-            int j;
+            int16_t j;
             for (j = 0; j < KM_IN; j++) {
                 bool new_b = new & BIT(j);
                 bool last_b = last & BIT(j);
diff --git a/src/board/system76/common/keymap.c b/src/board/system76/common/keymap.c
index 91196df..c0094c8 100644
--- a/src/board/system76/common/keymap.c
+++ b/src/board/system76/common/keymap.c
@@ -17,9 +17,9 @@ void keymap_init(void) {
 }
 
 void keymap_load_default(void) {
-    for (int layer = 0; layer < KM_LAY; layer++) {
-        for (int output = 0; output < KM_OUT; output++) {
-            for (int input = 0; input < KM_IN; input++) {
+    for (int16_t layer = 0; layer < KM_LAY; layer++) {
+        for (int16_t output = 0; output < KM_OUT; output++) {
+            for (int16_t input = 0; input < KM_IN; input++) {
                 DYNAMIC_KEYMAP[layer][output][input] = KEYMAP[layer][output][input];
             }
         }
@@ -57,7 +57,7 @@ bool keymap_save_config(void) {
     return flash_read_u16(CONFIG_ADDR) == CONFIG_SIGNATURE;
 }
 
-bool keymap_get(int layer, int output, int input, uint16_t * value) {
+bool keymap_get(int16_t layer, int16_t output, int16_t input, uint16_t * value) {
     if (layer < KM_LAY && output < KM_OUT && input < KM_IN) {
         *value = DYNAMIC_KEYMAP[layer][output][input];
         return true;
@@ -66,7 +66,7 @@ bool keymap_get(int layer, int output, int input, uint16_t * value) {
     }
 }
 
-bool keymap_set(int layer, int output, int input, uint16_t value) {
+bool keymap_set(int16_t layer, int16_t output, int16_t input, uint16_t value) {
     if (layer < KM_LAY && output < KM_OUT && input < KM_IN) {
         DYNAMIC_KEYMAP[layer][output][input] = value;
         return true;
diff --git a/src/board/system76/common/parallel.c b/src/board/system76/common/parallel.c
index ff0c0e9..fd460a3 100644
--- a/src/board/system76/common/parallel.c
+++ b/src/board/system76/common/parallel.c
@@ -82,14 +82,14 @@ bool parallel_init(void) {
     return parallel_wait_peripheral(STS_WAIT, 0);
 }
 
-int parallel_write(uint8_t * data, int length) {
+int16_t parallel_write(uint8_t * data, int16_t length) {
     // Assert nWRITE
     KSIGDAT &= ~CTL_WRITE;
 
     // Set data lines as outputs
     KSOLGOEN = 0xFF;
 
-    int i;
+    int16_t i;
     for (i = 0; i < length; i++) {
         // Wait for peripheral to indicate it's ready for next cycle
         if (!parallel_wait_peripheral(STS_WAIT, 0)) {
diff --git a/src/board/system76/common/peci.c b/src/board/system76/common/peci.c
index 4b333a6..00dc989 100644
--- a/src/board/system76/common/peci.c
+++ b/src/board/system76/common/peci.c
@@ -69,7 +69,7 @@ void peci_init(void) {
 
 // Returns positive completion code on success, negative completion code or
 // negative (0x1000 | status register) on PECI hardware error
-int peci_wr_pkg_config(uint8_t index, uint16_t param, uint32_t data) {
+int16_t peci_wr_pkg_config(uint8_t index, uint16_t param, uint32_t data) {
     // Wait for completion
     while (HOSTAR & 1) {}
     // Clear status
@@ -105,9 +105,9 @@ int peci_wr_pkg_config(uint8_t index, uint16_t param, uint32_t data) {
     // Wait for completion
     while (HOSTAR & 1) {}
 
-    int status = (int)HOSTAR;
+    int16_t status = (int16_t)HOSTAR;
     if (status & BIT(1)) {
-        int cc = (int)HORDDR;
+        int16_t cc = (int16_t)HORDDR;
         if (cc & 0x80) {
             return -cc;
         } else {
diff --git a/src/board/system76/common/power.c b/src/board/system76/common/power.c
index 73b969c..594ec53 100644
--- a/src/board/system76/common/power.c
+++ b/src/board/system76/common/power.c
@@ -294,7 +294,7 @@ void power_on_s5(void) {
     // Wait for SUSPWRDNACK validity
     tPLT01;
 
-    for (int i = 0; i < 5000; i++) {
+    for (int16_t i = 0; i < 5000; i++) {
         // If we reached S0, exit this loop
         update_power_state();
         if (power_state == POWER_STATE_S0) {
@@ -361,9 +361,9 @@ void power_off_s5(void) {
 static void power_peci_limit(bool ac) {
     uint8_t watts = ac ? POWER_LIMIT_AC : POWER_LIMIT_DC;
     // Retry, timeout errors happen occasionally
-    for (int i = 0; i < 16; i++) {
+    for (int16_t i = 0; i < 16; i++) {
         // Set PL4 using PECI
-        int res = peci_wr_pkg_config(60, 0, ((uint32_t)watts) * 8);
+        int16_t res = peci_wr_pkg_config(60, 0, ((uint32_t)watts) * 8);
         DEBUG("power_peci_limit %d = %d\n", watts, res);
         if (res == 0x40) {
             break;
@@ -466,7 +466,7 @@ void power_event(void) {
     bool ps_new = gpio_get(&PWR_SW_N);
     if (!ps_new && ps_last) {
         // Ensure press is not spurious
-        for (int i = 0; i < 100; i++) {
+        for (int16_t i = 0; i < 100; i++) {
             delay_ms(1);
             if (gpio_get(&PWR_SW_N) != ps_new) {
                 DEBUG("%02X: Spurious press\n", main_cycle);
diff --git a/src/board/system76/common/scratch/stdio.c b/src/board/system76/common/scratch/stdio.c
index 273947c..9ca2f8b 100644
--- a/src/board/system76/common/scratch/stdio.c
+++ b/src/board/system76/common/scratch/stdio.c
@@ -5,7 +5,7 @@
 #include <board/smfi.h>
 
 int putchar(int c) {
-    unsigned char byte = (unsigned char)c;
+    uint8_t byte = (uint8_t)c;
     smfi_debug(byte);
     return (int)byte;
 }
diff --git a/src/board/system76/common/smbus.c b/src/board/system76/common/smbus.c
index 5233ec7..fcc8120 100644
--- a/src/board/system76/common/smbus.c
+++ b/src/board/system76/common/smbus.c
@@ -22,10 +22,10 @@ void smbus_init(void) {
     i2c_reset(&I2C_SMBUS, true);
 }
 
-int smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
+int16_t smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
     return i2c_get(&I2C_SMBUS, address, command, (uint8_t *)data, 2);
 }
 
-int smbus_write(uint8_t address, uint8_t command, uint16_t data) {
+int16_t smbus_write(uint8_t address, uint8_t command, uint16_t data) {
     return i2c_set(&I2C_SMBUS, address, command, (uint8_t *)&data, 2);
 }
diff --git a/src/board/system76/common/smfi.c b/src/board/system76/common/smfi.c
index 42cb551..dffb638 100644
--- a/src/board/system76/common/smfi.c
+++ b/src/board/system76/common/smfi.c
@@ -71,7 +71,7 @@ static volatile uint8_t __xdata __at(0xF00) smfi_dbg[256];
 
 #if !defined(__SCRATCH__)
 void smfi_init(void) {
-    int i;
+    int16_t i;
 
     // Clear command region
     for (i = (SMFI_CMD_CMD + 1); i < ARRAY_SIZE(smfi_cmd); i++) {
@@ -151,9 +151,9 @@ static enum Result cmd_fan_set(void) {
 }
 
 static enum Result cmd_keymap_get(void) {
-    int layer = smfi_cmd[SMFI_CMD_DATA];
-    int output = smfi_cmd[SMFI_CMD_DATA + 1];
-    int input = smfi_cmd[SMFI_CMD_DATA + 2];
+    int16_t layer = smfi_cmd[SMFI_CMD_DATA];
+    int16_t output = smfi_cmd[SMFI_CMD_DATA + 1];
+    int16_t input = smfi_cmd[SMFI_CMD_DATA + 2];
     uint16_t key = 0;
     if (keymap_get(layer, output, input, &key)) {
         smfi_cmd[SMFI_CMD_DATA + 3] = (uint8_t)key;
@@ -165,9 +165,9 @@ static enum Result cmd_keymap_get(void) {
 }
 
 static enum Result cmd_keymap_set(void) {
-    int layer = smfi_cmd[SMFI_CMD_DATA];
-    int output = smfi_cmd[SMFI_CMD_DATA + 1];
-    int input = smfi_cmd[SMFI_CMD_DATA + 2];
+    int16_t layer = smfi_cmd[SMFI_CMD_DATA];
+    int16_t output = smfi_cmd[SMFI_CMD_DATA + 1];
+    int16_t input = smfi_cmd[SMFI_CMD_DATA + 2];
     uint16_t key =
         ((uint16_t)smfi_cmd[SMFI_CMD_DATA + 3]) |
         (((uint16_t)smfi_cmd[SMFI_CMD_DATA + 4]) << 8);
@@ -389,8 +389,8 @@ void smfi_event(void) {
     }
 }
 
-void smfi_debug(unsigned char byte) {
-    int tail = (int)smfi_dbg[SMFI_DBG_TAIL];
+void smfi_debug(uint8_t byte) {
+    int16_t tail = (int16_t)smfi_dbg[SMFI_DBG_TAIL];
     tail++;
     if (tail >= ARRAY_SIZE(smfi_dbg)) {
         tail = SMFI_DBG_TAIL + 1;
diff --git a/src/board/system76/common/stdio.c b/src/board/system76/common/stdio.c
index fc925e9..eae821f 100644
--- a/src/board/system76/common/stdio.c
+++ b/src/board/system76/common/stdio.c
@@ -17,7 +17,7 @@
 #endif // PARALLEL_DEBUG
 
 int putchar(int c) {
-    unsigned char byte = (unsigned char)c;
+    uint8_t byte = (uint8_t)c;
 
     smfi_debug(byte);
 
diff --git a/src/common/i2c.c b/src/common/i2c.c
index c1b4e98..e35faa8 100644
--- a/src/common/i2c.c
+++ b/src/common/i2c.c
@@ -2,8 +2,8 @@
 
 #include <common/i2c.h>
 
-int i2c_recv(struct I2C * i2c, uint8_t addr, uint8_t* data, int length) __reentrant {
-    int res = 0;
+int16_t i2c_recv(struct I2C * i2c, uint8_t addr, uint8_t* data, int16_t length) __reentrant {
+    int16_t res = 0;
 
     res = i2c_start(i2c, addr, true);
     if (res < 0) return res;
@@ -16,8 +16,8 @@ int i2c_recv(struct I2C * i2c, uint8_t addr, uint8_t* data, int length) __reentr
     return res;
 }
 
-int i2c_send(struct I2C * i2c, uint8_t addr, uint8_t* data, int length) __reentrant {
-    int res = 0;
+int16_t i2c_send(struct I2C * i2c, uint8_t addr, uint8_t* data, int16_t length) __reentrant {
+    int16_t res = 0;
 
     res = i2c_start(i2c, addr, false);
     if (res < 0) return res;
@@ -30,8 +30,8 @@ int i2c_send(struct I2C * i2c, uint8_t addr, uint8_t* data, int length) __reentr
     return res;
 }
 
-int i2c_get(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int length) __reentrant {
-    int res = 0;
+int16_t i2c_get(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int16_t length) __reentrant {
+    int16_t res = 0;
 
     res = i2c_start(i2c, addr, false);
     if (res < 0) return res;
@@ -42,8 +42,8 @@ int i2c_get(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int leng
     return i2c_recv(i2c, addr, data, length);
 }
 
-int i2c_set(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int length) __reentrant {
-    int res = 0;
+int16_t i2c_set(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int16_t length) __reentrant {
+    int16_t res = 0;
 
     res = i2c_start(i2c, addr, false);
     if (res < 0) return res;
diff --git a/src/common/include/common/i2c.h b/src/common/include/common/i2c.h
index c8102fe..370630d 100644
--- a/src/common/include/common/i2c.h
+++ b/src/common/include/common/i2c.h
@@ -16,7 +16,7 @@ struct I2C;
 
 // Start i2c transaction
 // Must be defined by arch, board, or ec
-int i2c_start(struct I2C * i2c, uint8_t addr, bool read) __reentrant;
+int16_t i2c_start(struct I2C * i2c, uint8_t addr, bool read) __reentrant;
 
 // Stop i2c transaction
 // Must be defined by arch, board, or ec
@@ -24,22 +24,22 @@ void i2c_stop(struct I2C * i2c) __reentrant;
 
 // Send a byte on i2c bus
 // Must be defined by arch, board, or ec
-int i2c_write(struct I2C * i2c, uint8_t * data, int length) __reentrant;
+int16_t i2c_write(struct I2C * i2c, uint8_t * data, int16_t length) __reentrant;
 
 // Read bytes from bus
 // Must be defined by arch, board, or ec
-int i2c_read(struct I2C * i2c, uint8_t * data, int length) __reentrant;
+int16_t i2c_read(struct I2C * i2c, uint8_t * data, int16_t length) __reentrant;
 
 // Read multiple bytes from address in one transaction
-int i2c_recv(struct I2C * i2c, uint8_t addr, uint8_t* data, int length) __reentrant;
+int16_t i2c_recv(struct I2C * i2c, uint8_t addr, uint8_t* data, int16_t length) __reentrant;
 
 // Write multiple bytes to address in one transaction
-int i2c_send(struct I2C * i2c, uint8_t addr, uint8_t* data, int length) __reentrant;
+int16_t i2c_send(struct I2C * i2c, uint8_t addr, uint8_t* data, int16_t length) __reentrant;
 
 // Read multiple bytes from a register in one transaction
-int i2c_get(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int length) __reentrant;
+int16_t i2c_get(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int16_t length) __reentrant;
 
 // Write multiple bytes to a register in one transaction
-int i2c_set(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int length) __reentrant;
+int16_t i2c_set(struct I2C * i2c, uint8_t addr, uint8_t reg, uint8_t* data, int16_t length) __reentrant;
 
 #endif // _COMMON_I2C_H
diff --git a/src/common/include/common/keymap.h b/src/common/include/common/keymap.h
index 16a3307..7f1d0f0 100644
--- a/src/common/include/common/keymap.h
+++ b/src/common/include/common/keymap.h
@@ -27,9 +27,9 @@
     // Save dynamic keymap to flash
     bool keymap_save_config(void);
     // Get a keycode from the dynamic keymap
-    bool keymap_get(int layer, int output, int input, uint16_t * value);
+    bool keymap_get(int16_t layer, int16_t output, int16_t input, uint16_t * value);
     // Set a keycode in the dynamic keymap
-    bool keymap_set(int layer, int output, int input, uint16_t value);
+    bool keymap_set(int16_t layer, int16_t output, int16_t input, uint16_t value);
 #endif
 
 // Translate a keycode from PS/2 set 2 to PS/2 set 1
diff --git a/src/ec/ite/i2c.c b/src/ec/ite/i2c.c
index b0bd492..51c7caa 100644
--- a/src/ec/ite/i2c.c
+++ b/src/ec/ite/i2c.c
@@ -57,7 +57,7 @@ void i2c_reset(struct I2C * i2c, bool kill) {
     *(i2c->hoctl2) = 0;
 }
 
-int i2c_start(struct I2C * i2c, uint8_t addr, bool read) __reentrant {
+int16_t i2c_start(struct I2C * i2c, uint8_t addr, bool read) __reentrant {
     // If we are already in a transaction
     if (*(i2c->hosta) & HOSTA_BYTE_DONE) {
         // If we are switching direction
@@ -94,8 +94,8 @@ void i2c_stop(struct I2C * i2c) {
     i2c_reset(i2c, false);
 }
 
-static int i2c_transaction(struct I2C * i2c, uint8_t * data, int length, bool read) {
-    int i;
+static int16_t i2c_transaction(struct I2C * i2c, uint8_t * data, int16_t length, bool read) {
+    int16_t i;
     for (i = 0; i < length; i++) {
         if (read) {
             // If last byte
@@ -131,7 +131,7 @@ static int i2c_transaction(struct I2C * i2c, uint8_t * data, int length, bool re
             // If error occured, kill transaction and return error
             if (status & HOSTA_ERR) {
                 i2c_reset(i2c, true);
-                return -(int)(status);
+                return -(int16_t)(status);
             } else
             // If byte done, break
             if (status & HOSTA_BYTE_DONE) {
@@ -141,7 +141,7 @@ static int i2c_transaction(struct I2C * i2c, uint8_t * data, int length, bool re
         // If timeout occured, kill transaction and return error
         if (timeout == 0) {
             i2c_reset(i2c, true);
-            return -(0x1000 | (int)status);
+            return -(0x1000 | (int16_t)status);
         }
 
         if (read) {
@@ -153,10 +153,10 @@ static int i2c_transaction(struct I2C * i2c, uint8_t * data, int length, bool re
     return i;
 }
 
-int i2c_read(struct I2C * i2c, uint8_t * data, int length) __reentrant {
+int16_t i2c_read(struct I2C * i2c, uint8_t * data, int16_t length) __reentrant {
     return i2c_transaction(i2c, data, length, true);
 }
 
-int i2c_write(struct I2C * i2c, uint8_t * data, int length) __reentrant {
+int16_t i2c_write(struct I2C * i2c, uint8_t * data, int16_t length) __reentrant {
     return i2c_transaction(i2c, data, length, false);
 }
diff --git a/src/ec/ite/include/ec/kbc.h b/src/ec/ite/include/ec/kbc.h
index 2467c8f..163f72d 100644
--- a/src/ec/ite/include/ec/kbc.h
+++ b/src/ec/ite/include/ec/kbc.h
@@ -33,8 +33,8 @@ extern struct Kbc __code KBC;
 
 uint8_t kbc_status(struct Kbc * kbc);
 uint8_t kbc_read(struct Kbc * kbc);
-bool kbc_keyboard(struct Kbc * kbc, uint8_t data, int timeout);
-bool kbc_mouse(struct Kbc * kbc, uint8_t data, int timeout);
+bool kbc_keyboard(struct Kbc * kbc, uint8_t data, int16_t timeout);
+bool kbc_mouse(struct Kbc * kbc, uint8_t data, int16_t timeout);
 
 volatile uint8_t __xdata __at(0x1300) KBHICR;
 volatile uint8_t __xdata __at(0x1302) KBIRQR;
diff --git a/src/ec/ite/kbc.c b/src/ec/ite/kbc.c
index 7f70ec6..47da946 100644
--- a/src/ec/ite/kbc.c
+++ b/src/ec/ite/kbc.c
@@ -20,7 +20,7 @@ uint8_t kbc_read(struct Kbc * kbc) {
     return *(kbc->data_in);
 }
 
-static bool kbc_wait(struct Kbc * kbc, int timeout) {
+static bool kbc_wait(struct Kbc * kbc, int16_t timeout) {
     while (*(kbc->status) & KBC_STS_OBF) {
         if (timeout == 0) return false;
         timeout -= 1;
@@ -29,14 +29,14 @@ static bool kbc_wait(struct Kbc * kbc, int timeout) {
     return true;
 }
 
-bool kbc_keyboard(struct Kbc * kbc, uint8_t data, int timeout) {
+bool kbc_keyboard(struct Kbc * kbc, uint8_t data, int16_t timeout) {
     if (!kbc_wait(kbc, timeout)) return false;
     *(kbc->status) &= ~0x20;
     *(kbc->keyboard_out) = data;
     return true;
 }
 
-bool kbc_mouse(struct Kbc * kbc, uint8_t data, int timeout) {
+bool kbc_mouse(struct Kbc * kbc, uint8_t data, int16_t timeout) {
     if (!kbc_wait(kbc, timeout)) return false;
     *(kbc->status) |= 0x20;
     *(kbc->mouse_out) = data;
diff --git a/src/ec/ite/signature.c b/src/ec/ite/signature.c
index 477da26..c9d8270 100644
--- a/src/ec/ite/signature.c
+++ b/src/ec/ite/signature.c
@@ -4,13 +4,13 @@
 
 #if EC_ESPI
 // eSPI signature (byte 7 = 0xA4)
-static __code const unsigned char __at(0x40) SIGNATURE[16] = {
+static __code const uint8_t __at(0x40) SIGNATURE[16] = {
     0xA5, 0xA5, 0xA5, 0xA5, 0xA5, 0xA5, 0xA4, 0x95,
     0x85, 0x12, 0x5A, 0x5A, 0xAA, 0x00, 0x55, 0x55,
 };
 #else // EC_ESPI
 // LPC signature (byte 7 = 0xA5)
-static __code const unsigned char __at(0x40) SIGNATURE[16] = {
+static __code const uint8_t __at(0x40) SIGNATURE[16] = {
     0xA5, 0xA5, 0xA5, 0xA5, 0xA5, 0xA5, 0xA5, 0x94,
     0x85, 0x12, 0x5A, 0x5A, 0xAA, 0x00, 0x55, 0x55,
 };