diff --git a/.github/workflows/act.yml b/.github/workflows/act.yml
new file mode 100644
index 0000000..0d5aa16
--- /dev/null
+++ b/.github/workflows/act.yml
@@ -0,0 +1,11 @@
+name: act-build 
+
+jobs:
+  act-linux:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - run: apt-get update
+    - run: apt install sudo
+    - run: sudo apt -y install gcc-arm-none-eabi make openocd git
+    - run: make
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index f39dd82..aac916d 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -12,5 +12,5 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - run: sudo apt-get update
-    - run: sudo apt -y install gcc-arm-none-eabi make openocd
+    - run: sudo apt -y install gcc-arm-none-eabi make openocd git
     - run: make
diff --git a/Makefile b/Makefile
index cea9f6e..0196b0d 100644
--- a/Makefile
+++ b/Makefile
@@ -79,4 +79,7 @@ debug:
 	@openocd -f interface/stlink.cfg -f board/stm32f0discovery.cfg -c "init" &
 	@arm-none-eabi-gdb bin/firmware.elf -x gdbconf
 
-.PHONY: all dep cmsis_core cmsis_f0 build clean dep_clean flash debug
+test:
+	@act --job act-linux
+
+.PHONY: all dep cmsis_core cmsis_f0 build clean dep_clean flash debug test
diff --git a/src/hal/.hal.h.swp b/src/hal/.hal.h.swp
new file mode 100644
index 0000000..f3c92e4
Binary files /dev/null and b/src/hal/.hal.h.swp differ
diff --git a/src/hal/hal.c b/src/hal/hal.c
index 3d3762d..38f20d4 100644
--- a/src/hal/hal.c
+++ b/src/hal/hal.c
@@ -42,7 +42,7 @@ uint8_t gpio_read(uint16_t pin)
 void rcc_port_set(uint8_t bank, uint8_t mode)
 {
 	int n = (17 + bank);
-	RCC->AHBENR = (RCC->AHBENR & ~BIT(n)) | (mode << n);  /* Clear, then set bit. */
+	RCC->AHBENR = (RCC->AHBENR & ~BIT(n)) | (uint32_t)(mode << n);  /* Clear, then set bit. */
 }
 
 int timer_expired(uint32_t *t, uint32_t prd, uint32_t now)
@@ -71,7 +71,7 @@ void exti_pin_init(uint16_t pin, uint8_t rising, uint8_t priority, func_ptr hand
 	volatile uint32_t *edge_selection = (&EXTI->FTSR - rising);  /* Rising/falling edge. */
 	*edge_selection |= BIT(n);
 
-	SYSCFG->EXTICR[n / 4] |= PIN_BANK(pin) << ((n - (4 * (n / 4))) * 4);  /* Set source input for respective EXTI line. */
+	SYSCFG->EXTICR[n / 4] |= (uint32_t)(PIN_BANK(pin) << ((n - (4 * (n / 4))) * 4));  /* Set source input for respective EXTI line. */
 	
 	uint8_t irq_pos = n < 2 ? EXTI0_1_IRQn : n < 4 ? EXTI2_3_IRQn : EXTI4_15_IRQn;
 	NVIC_EnableIRQ(irq_pos);
diff --git a/src/hal/hal.h b/src/hal/hal.h
index 98ee7ce..927bc7f 100644
--- a/src/hal/hal.h
+++ b/src/hal/hal.h
@@ -21,8 +21,8 @@
 #define BIT_LAST(x, y) (x & ((1UL << y) - 1))  /* Last y bits. */
 
 /* uint16_t(2 bytes): upper byte = bank #, lower byte = pin # */
-#define PIN(bank, num) ((((bank) - 'A') << 8) | (num))  /* ex: PIN('C', 7) */
-#define PIN_NUM(pin) ((uint8_t)BIT_LAST(pin, 8))
+#define PIN(bank, num) ((uint16_t)((uint16_t)((uint8_t)(bank) - 'A') << 8UL) | (uint16_t)(num))
+#define PIN_NUM(pin) ((uint8_t)(BIT_LAST(pin, 8)))
 #define PIN_BANK(pin) ((uint8_t)((pin) >> 8))
 
 /* GPIO input/output modes. */