diff --git a/board/drivers/uart.h b/board/drivers/uart.h
index 01d8c2ac..e9a7c507 100644
--- a/board/drivers/uart.h
+++ b/board/drivers/uart.h
@@ -37,8 +37,6 @@ typedef struct uart_ring {
 // ***************************** Function prototypes *****************************
 void debug_ring_callback(uart_ring *ring);
 void uart_tx_ring(uart_ring *q);
-void uart_send_break(uart_ring *u);
-
 // ******************************** UART buffers ********************************
 
 // debug = USART2
diff --git a/board/stm32f4/llfan.h b/board/stm32f4/llfan.h
index 9e3f0c65..95861661 100644
--- a/board/stm32f4/llfan.h
+++ b/board/stm32f4/llfan.h
@@ -1,5 +1,5 @@
 // TACH interrupt handler
-void EXTI2_IRQ_Handler(void) {
+static void EXTI2_IRQ_Handler(void) {
   volatile unsigned int pr = EXTI->PR & (1U << 2);
   if ((pr & (1U << 2)) != 0U) {
     fan_state.tach_counter++;
diff --git a/board/stm32f4/llspi.h b/board/stm32f4/llspi.h
index 31e419b6..a83e322c 100644
--- a/board/stm32f4/llspi.h
+++ b/board/stm32f4/llspi.h
@@ -31,7 +31,7 @@ void llspi_mosi_dma(uint8_t *addr, int len) {
 }
 
 // SPI MOSI DMA FINISHED
-void DMA2_Stream2_IRQ_Handler(void) {
+static void DMA2_Stream2_IRQ_Handler(void) {
   // Clear interrupt flag
   ENTER_CRITICAL();
   DMA2->LIFCR = DMA_LIFCR_CTCIF2;
@@ -42,7 +42,7 @@ void DMA2_Stream2_IRQ_Handler(void) {
 }
 
 // SPI MISO DMA FINISHED
-void DMA2_Stream3_IRQ_Handler(void) {
+static void DMA2_Stream3_IRQ_Handler(void) {
   // Clear interrupt flag
   DMA2->LIFCR = DMA_LIFCR_CTCIF3;
 
diff --git a/board/stm32f4/lluart.h b/board/stm32f4/lluart.h
index 64094119..f4b1a5f1 100644
--- a/board/stm32f4/lluart.h
+++ b/board/stm32f4/lluart.h
@@ -20,7 +20,7 @@ void uart_tx_ring(uart_ring *q){
   EXIT_CRITICAL();
 }
 
-void uart_rx_ring(uart_ring *q){
+static void uart_rx_ring(uart_ring *q){
   ENTER_CRITICAL();
 
   // Read out RX buffer
@@ -45,15 +45,10 @@ void uart_rx_ring(uart_ring *q){
   EXIT_CRITICAL();
 }
 
-void uart_send_break(uart_ring *u) {
-  while ((u->uart->CR1 & USART_CR1_SBK) != 0U);
-  u->uart->CR1 |= USART_CR1_SBK;
-}
-
 // This read after reading SR clears all error interrupts. We don't want compiler warnings, nor optimizations
 #define UART_READ_DR(uart) volatile uint8_t t = (uart)->DR; UNUSED(t);
 
-void uart_interrupt_handler(uart_ring *q) {
+static void uart_interrupt_handler(uart_ring *q) {
   ENTER_CRITICAL();
 
   // Read UART status. This is also the first step necessary in clearing most interrupts
diff --git a/board/stm32f4/peripherals.h b/board/stm32f4/peripherals.h
index 711f1b82..9c0b8ee6 100644
--- a/board/stm32f4/peripherals.h
+++ b/board/stm32f4/peripherals.h
@@ -1,4 +1,8 @@
+#ifdef BOOTSTUB
 void gpio_usb_init(void) {
+#else
+static void gpio_usb_init(void) {
+#endif
   // A11,A12: USB
   set_gpio_alternate(GPIOA, 11, GPIO_AF10_OTG_FS);
   set_gpio_alternate(GPIOA, 12, GPIO_AF10_OTG_FS);
diff --git a/board/stm32h7/clock.h b/board/stm32h7/clock.h
index b68fcc1c..4a29d459 100644
--- a/board/stm32h7/clock.h
+++ b/board/stm32h7/clock.h
@@ -25,7 +25,7 @@ typedef enum {
 
 // TODO: find a better way to distinguish between H725 (using SMPS) and H723 (lacking SMPS)
 // The package will do for now, since we have only used TFBGA100 for H723
-PackageSMPSType get_package_smps_type(void) {
+static PackageSMPSType get_package_smps_type(void) {
   PackageSMPSType ret;
   RCC->APB4ENR |= RCC_APB4ENR_SYSCFGEN; // make sure SYSCFG clock is enabled. does seem to read fine without too though
 
diff --git a/board/stm32h7/lladc.h b/board/stm32h7/lladc.h
index 7d818f27..248fa310 100644
--- a/board/stm32h7/lladc.h
+++ b/board/stm32h7/lladc.h
@@ -14,7 +14,7 @@ void adc_init(void) {
   while(!(ADC1->ISR & ADC_ISR_ADRDY));
 }
 
-uint16_t adc_get_raw(uint8_t channel) {
+static uint16_t adc_get_raw(uint8_t channel) {
   uint16_t res = 0U;
   ADC1->SQR1 &= ~(ADC_SQR1_L);
   ADC1->SQR1 = (uint32_t)channel << 6U;
diff --git a/board/stm32h7/llfan.h b/board/stm32h7/llfan.h
index 04f0fc11..06309d06 100644
--- a/board/stm32h7/llfan.h
+++ b/board/stm32h7/llfan.h
@@ -1,5 +1,5 @@
 // TACH interrupt handler
-void EXTI2_IRQ_Handler(void) {
+static void EXTI2_IRQ_Handler(void) {
   volatile unsigned int pr = EXTI->PR1 & (1U << 2);
   if ((pr & (1U << 2)) != 0U) {
     fan_state.tach_counter++;
diff --git a/board/stm32h7/llspi.h b/board/stm32h7/llspi.h
index 903f6a5e..5a18a742 100644
--- a/board/stm32h7/llspi.h
+++ b/board/stm32h7/llspi.h
@@ -49,7 +49,7 @@ void llspi_miso_dma(uint8_t *addr, int len) {
 }
 
 // master -> panda DMA finished
-void DMA2_Stream2_IRQ_Handler(void) {
+static void DMA2_Stream2_IRQ_Handler(void) {
   // Clear interrupt flag
   DMA2->LIFCR = DMA_LIFCR_CTCIF2;
 
@@ -57,7 +57,7 @@ void DMA2_Stream2_IRQ_Handler(void) {
 }
 
 // panda -> master DMA finished
-void DMA2_Stream3_IRQ_Handler(void) {
+static void DMA2_Stream3_IRQ_Handler(void) {
   ENTER_CRITICAL();
 
   DMA2->LIFCR = DMA_LIFCR_CTCIF3;
@@ -67,7 +67,7 @@ void DMA2_Stream3_IRQ_Handler(void) {
 }
 
 // panda TX finished
-void SPI4_IRQ_Handler(void) {
+static void SPI4_IRQ_Handler(void) {
   // clear flag
   SPI4->IFCR |= (0x1FFU << 3U);
 
diff --git a/board/stm32h7/lluart.h b/board/stm32h7/lluart.h
index 6ca6dcec..742549bb 100644
--- a/board/stm32h7/lluart.h
+++ b/board/stm32h7/lluart.h
@@ -1,4 +1,4 @@
-void uart_rx_ring(uart_ring *q){
+static void uart_rx_ring(uart_ring *q){
   // Do not read out directly if DMA enabled
   ENTER_CRITICAL();
 
@@ -52,7 +52,7 @@ void uart_set_baud(USART_TypeDef *u, unsigned int baud) {
 // This read after reading ISR clears all error interrupts. We don't want compiler warnings, nor optimizations
 #define UART_READ_RDR(uart) volatile uint8_t t = (uart)->RDR; UNUSED(t);
 
-void uart_interrupt_handler(uart_ring *q) {
+static void uart_interrupt_handler(uart_ring *q) {
   ENTER_CRITICAL();
 
   // Read UART status. This is also the first step necessary in clearing most interrupts
@@ -88,7 +88,7 @@ void uart_interrupt_handler(uart_ring *q) {
   EXIT_CRITICAL();
 }
 
-void UART7_IRQ_Handler(void) { uart_interrupt_handler(&uart_ring_som_debug); }
+static void UART7_IRQ_Handler(void) { uart_interrupt_handler(&uart_ring_som_debug); }
 
 void uart_init(uart_ring *q, int baud) {
   if (q->uart == UART7) {
diff --git a/board/stm32h7/peripherals.h b/board/stm32h7/peripherals.h
index b60f1901..b9a58612 100644
--- a/board/stm32h7/peripherals.h
+++ b/board/stm32h7/peripherals.h
@@ -1,4 +1,8 @@
+#ifdef BOOTSTUB
 void gpio_usb_init(void) {
+#else
+static void gpio_usb_init(void) {
+#endif
   // A11,A12: USB
   set_gpio_alternate(GPIOA, 11, GPIO_AF10_OTG1_FS);
   set_gpio_alternate(GPIOA, 12, GPIO_AF10_OTG1_FS);