diff --git a/src/timer.c b/src/timer.c
index cb794d3..0bec1bd 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -18,5 +18,5 @@ void tim4_init(void) {
 }
 
 void tim4_start(void) {
-  TIM4->CR1 |= TIM4_ENABLE;
+  TIM4->CR1 |= TIM_ENABLE;
 }
diff --git a/src/timer.h b/src/timer.h
index 18eebc4..3b386de 100644
--- a/src/timer.h
+++ b/src/timer.h
@@ -29,8 +29,8 @@ struct timer {
 #define TIM4_BASE_ADDR (0x40000800U)
 #define TIM4 ((struct timer *) TIM4_BASE_ADDR)
 
-#define TIM4_CR_CEN_BIT 0
-#define TIM4_ENABLE (1 << TIM4_CR_CEN_BIT)
+#define TIM_CR1_CEN_BIT 0
+#define TIM_ENABLE (1 << TIM_CR1_CEN_BIT)
 
 void tim4_init(void);
 void tim4_start(void);