diff --git a/board/bootstub.c b/board/bootstub.c
index b490a07..1df3922 100644
--- a/board/bootstub.c
+++ b/board/bootstub.c
@@ -37,11 +37,11 @@ int main() {
   clock_init();
 
   // validate length
-  int len = _app_start[0];
+  int len = (int)_app_start[0];
   if (len < 8) fail();
 
   // compute SHA hash
-  char digest[SHA_DIGEST_SIZE];
+  uint8_t digest[SHA_DIGEST_SIZE];
   SHA_hash(&_app_start[1], len-4, digest);
 
   // verify RSA signature
diff --git a/board/build.mk b/board/build.mk
index d7e28f0..b0a7490 100644
--- a/board/build.mk
+++ b/board/build.mk
@@ -1,4 +1,4 @@
-CFLAGS += -I inc -I ../ -nostdlib
+CFLAGS += -I inc -I ../ -nostdlib -fno-builtin
 CFLAGS += -Tstm32_flash.ld
 
 CC = arm-none-eabi-gcc
diff --git a/board/early.h b/board/early.h
index e5f3db0..ca28113 100644
--- a/board/early.h
+++ b/board/early.h
@@ -3,6 +3,7 @@
 extern uint32_t enter_bootloader_mode;
 extern void *_app_start[];
 void *g_pfnVectors;
+void spi_flasher();
 
 int has_external_debug_serial = 0;
 int is_giant_panda = 0;
diff --git a/board/main.c b/board/main.c
index e235b12..69db9b8 100644
--- a/board/main.c
+++ b/board/main.c
@@ -97,6 +97,7 @@ typedef struct uart_ring {
   void (*callback)(struct uart_ring*);
 } uart_ring;
 
+inline int getc(uart_ring *q, char *elem);
 inline int putc(uart_ring *q, char elem);
 
 // esp = USART1
@@ -141,7 +142,7 @@ void accord_framing_callback(uart_ring *q) {
   int sof1 = -1;
   int sof2 = -1;
   int i;
-  uint8_t junk;
+  char junk;
   int jlen = 0;
   int plen = 0;
   while (q->w_ptr_rx != r_ptr_rx_tmp) {
@@ -189,7 +190,7 @@ void accord_framing_callback(uart_ring *q) {
 
       // get data from queue
       for (i = 0; i < plen; i++) {
-        getc(q, &(((uint8_t*)(&to_push.RDLR))[i]));
+        getc(q, &(((char*)(&to_push.RDLR))[i]));
       }
 
       push(&can_rx_q, &to_push);
@@ -511,7 +512,6 @@ void usb_cb_ep3_out(uint8_t *usbdata, int len, int hardwired) {
     if (safety_tx_hook(&to_push, hardwired)) {
       CAN_TypeDef *CAN;
       can_ring *can_q;
-      int can_number;
       if (flags == can_numbering[0])  {
         CAN = CAN1;
         can_q = &can_tx1_q;
@@ -562,11 +562,12 @@ int usb_cb_control_msg(USB_Setup_TypeDef *setup, uint8_t *resp, int hardwired) {
     case 0xd0:
       // fetch serial number
       #ifdef PANDA
+        // addresses are OTP
         if (setup->b.wValue.w == 1) {
-          memcpy(resp, 0x1fff79c0, 0x10);
+          memcpy(resp, (void *)0x1fff79c0, 0x10);
           resp_len = 0x10;
         } else {
-          memcpy(resp, 0x1fff79e0, 0x20);
+          memcpy(resp, (void *)0x1fff79e0, 0x20);
           resp_len = 0x20;
         }
       #endif
@@ -625,7 +626,7 @@ int usb_cb_control_msg(USB_Setup_TypeDef *setup, uint8_t *resp, int hardwired) {
       ur = get_ring_by_number(setup->b.wValue.w);
       if (!ur) break;
       // read
-      while (resp_len < min(setup->b.wLength.w, MAX_RESP_LEN) && getc(ur, &resp[resp_len])) {
+      while (resp_len < min(setup->b.wLength.w, MAX_RESP_LEN) && getc(ur, (char*)&resp[resp_len])) {
         ++resp_len;
       }
       break;
diff --git a/board/spi.h b/board/spi.h
index ab2e865..2b5e4cd 100644
--- a/board/spi.h
+++ b/board/spi.h
@@ -13,9 +13,9 @@ void spi_tx_dma(void *addr, int len) {
   DMA2_Stream3->CR &= ~DMA_SxCR_EN;
 
   // DMA2, stream 3, channel 3
-  DMA2_Stream3->M0AR = addr;
+  DMA2_Stream3->M0AR = (uint32_t)addr;
   DMA2_Stream3->NDTR = len;
-  DMA2_Stream3->PAR = &(SPI1->DR);
+  DMA2_Stream3->PAR = (uint32_t)&(SPI1->DR);
 
   // channel3, increment memory, memory -> periph, enable
   DMA2_Stream3->CR = DMA_SxCR_CHSEL_1 | DMA_SxCR_CHSEL_0 | DMA_SxCR_MINC | DMA_SxCR_DIR_0 | DMA_SxCR_EN;
@@ -31,11 +31,12 @@ void spi_rx_dma(void *addr, int len) {
 
   // drain the bus
   uint8_t dat = SPI1->DR;
+  (void)dat;
 
   // DMA2, stream 2, channel 3
-  DMA2_Stream2->M0AR = addr;
+  DMA2_Stream2->M0AR = (uint32_t)addr;
   DMA2_Stream2->NDTR = len;
-  DMA2_Stream2->PAR = &(SPI1->DR);
+  DMA2_Stream2->PAR = (uint32_t)&(SPI1->DR);
 
   // channel3, increment memory, periph -> memory, enable
   DMA2_Stream2->CR = DMA_SxCR_CHSEL_1 | DMA_SxCR_CHSEL_0 | DMA_SxCR_MINC | DMA_SxCR_EN;
diff --git a/board/usb.h b/board/usb.h
index 06b73cb..e5c0dde 100644
--- a/board/usb.h
+++ b/board/usb.h
@@ -286,13 +286,13 @@ void usb_setup() {
         case USB_DESC_TYPE_STRING:
           switch (setup.b.wValue.bw.msb) {
             case 0:
-              USB_WritePacket(string_0_desc, min(sizeof(string_0_desc), setup.b.wLength.w), 0);
+              USB_WritePacket((uint8_t*)string_0_desc, min(sizeof(string_0_desc), setup.b.wLength.w), 0);
               break;
             case 1:
-              USB_WritePacket(string_1_desc, min(sizeof(string_1_desc), setup.b.wLength.w), 0);
+              USB_WritePacket((uint8_t*)string_1_desc, min(sizeof(string_1_desc), setup.b.wLength.w), 0);
               break;
             case 2:
-              USB_WritePacket(string_2_desc, min(sizeof(string_2_desc), setup.b.wLength.w), 0);
+              USB_WritePacket((uint8_t*)string_2_desc, min(sizeof(string_2_desc), setup.b.wLength.w), 0);
               break;
             case 3:
               #ifdef PANDA
diff --git a/crypto/rsa.c b/crypto/rsa.c
index f98ba64..24171e8 100644
--- a/crypto/rsa.c
+++ b/crypto/rsa.c
@@ -226,7 +226,7 @@ int RSA_verify(const RSAPublicKey *key,
                const int hash_len) {
     uint8_t buf[RSANUMBYTES];
     int i;
-    const uint8_t* padding_hash;
+    //const uint8_t* padding_hash;
 
     if (key->len != RSANUMWORDS) {
         return 0;  // Wrong key passed in.
diff --git a/crypto/sha.c b/crypto/sha.c
index fa0ac26..47676df 100644
--- a/crypto/sha.c
+++ b/crypto/sha.c
@@ -27,6 +27,8 @@
 
 // Optimized for minimal code size.
 
+void *memcpy(void *str1, const void *str2, unsigned int n);
+
 #include "sha.h"
 
 #define rol(bits, value) (((value) << (bits)) | ((value) >> (32 - (bits))))