diff --git a/source/firmware/arch/stm32f4xx/syscalls.c b/source/firmware/arch/stm32f4xx/syscalls.c
index 180bda2..aa627e4 100755
--- a/source/firmware/arch/stm32f4xx/syscalls.c
+++ b/source/firmware/arch/stm32f4xx/syscalls.c
@@ -79,41 +79,29 @@ caddr_t _sbrk(int incr)
 
 int _close(int file)
 {
-    file = file; /* avoid warning */
     return -1;
 }
 
 int _fstat(int file, struct stat *st)
 {
-    file = file; /* avoid warning */
     st->st_mode = S_IFCHR;
     return 0;
 }
 
 int _isatty(int file)
 {
-    file = file; /* avoid warning */
     return 1;
 }
 
 int _lseek(int file, int ptr, int dir) {
-    file = file; /* avoid warning */
-    ptr = ptr; /* avoid warning */
-    dir = dir; /* avoid warning */
     return 0;
 }
 
 int _read(int file, char *ptr, int len)
 {
-    file = file; /* avoid warning */
-    ptr = ptr; /* avoid warning */
-    len = len; /* avoid warning */
     return 0;
 }
 
 int _write(int file, char *ptr, int len) {
-    int todo = todo;
-    file = file; /* avoid warning */
-//    USB_VCOM_Send(ptr, len);
     return len;
 }
diff --git a/source/firmware/kernel/driver/cc110x.c b/source/firmware/kernel/driver/cc110x.c
index 6f5a5a7..63aa5a0 100755
--- a/source/firmware/kernel/driver/cc110x.c
+++ b/source/firmware/kernel/driver/cc110x.c
@@ -103,11 +103,10 @@ int cc110x_write(const struct cc110x *cc110x, const char *buffer,
 int cc110x_read(const struct cc110x *cc110x, char *buffer, int size)
 {
 	int ret;
-	unsigned int irq;
 	if((NULL == cc110x) || (NULL == buffer))
 		return (-1);
 	if(0 == cc110x_get_rx_count(cc110x)) {
-		irq = disable_irq();
+		unsigned int irq = disable_irq();
 		current_thread->status = THREAD_STATUS_BLOCKING;
 		current_thread->wakeup_blocking_source = (void*) cc110x;
 		restore_irq(irq);
diff --git a/source/firmware/kernel/driver/ssd1306.c b/source/firmware/kernel/driver/ssd1306.c
index e045378..5bf62b2 100644
--- a/source/firmware/kernel/driver/ssd1306.c
+++ b/source/firmware/kernel/driver/ssd1306.c
@@ -101,7 +101,7 @@ int ssd1306_open(const struct ssd1306 *dev)
 {
 	int ret;
 	ret = i2c_open((struct i2c *)dev->dev);
-	ret = i2c_write(dev->dev, dev->i2c_addr, init_sequence,
+	ret |= i2c_write(dev->dev, dev->i2c_addr, init_sequence,
 			sizeof(init_sequence) / sizeof(init_sequence[0]));
 	ret |= clear(dev);
 	ret |= set_column(dev, 0);
diff --git a/source/firmware/kernel/thread.c b/source/firmware/kernel/thread.c
index 60ab76d..f6556af 100644
--- a/source/firmware/kernel/thread.c
+++ b/source/firmware/kernel/thread.c
@@ -108,8 +108,6 @@ struct thread_context *thread_create(
 		return NULL;
 
 	thread->pid = threads.count;
-	if(thread->pid < 0)
-		return NULL;
 	thread->stack = stack;
 	thread->stack_size = stack_size;
 	thread->sp = stack_init(thread_func, arg, stack, stack_size);