diff --git a/lib/usart.c b/lib/usart.c
index 18e0679..3ffcf0d 100644
--- a/lib/usart.c
+++ b/lib/usart.c
@@ -41,6 +41,7 @@
 #define USART_IRQ NVIC_USART1_IRQ /**< USART peripheral interrupt signal */
 #define USART_ISR usart1_isr /**< USART interrupt service routine */
 #define USART_PORT GPIOA /**< USART port */
+#define USART_PORT_RCC RCC_GPIOA /**< USART port peripheral clock */
 #define USART_PIN_TX GPIO_USART1_TX /**< USART transmit pin (PA9)  */
 #define USART_PIN_RX GPIO_USART1_RX /**< USART receive pin (PA10) */
 /** @} */
@@ -59,6 +60,7 @@ volatile uint8_t usart_received = 0; // same as rx_used, but since the user can
 void usart_setup(void)
 {
 	/* enable USART I/O peripheral */
+	rcc_periph_clock_enable(USART_PORT_RCC); // enable clock for USART port peripheral
 	rcc_periph_clock_enable(USART_RCC); // enable clock for USART peripheral
 	gpio_set_mode(USART_PORT, GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, USART_PIN_TX); // setup GPIO pin USART transmit
 	gpio_set_mode(USART_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, USART_PIN_RX); // setup GPIO pin USART receive