diff --git a/examples/stm32/stm32-h103/pwm_6step/pwm_6step.c b/examples/stm32/stm32-h103/pwm_6step/pwm_6step.c
index 9c04c9bd..cf53ac64 100644
--- a/examples/stm32/stm32-h103/pwm_6step/pwm_6step.c
+++ b/examples/stm32/stm32-h103/pwm_6step/pwm_6step.c
@@ -253,7 +253,8 @@ void tim1_trg_com_isr(void)
 {
 	static int step = 0;
 
-	TIM1_SR &= ~TIM_SR_COMIF;
+	/* Clear the COM trigger interrupt flag. */
+	timer_clear_flag(TIM1, TIM_SR_COMIF);
 
 	/* A simplified and inefficient implementation of PWM On
 	 * scheme. Look at the implementation in Open-BLDC on
diff --git a/include/libopencm3/stm32/timer.h b/include/libopencm3/stm32/timer.h
index 5d1c2357..c3bc1957 100644
--- a/include/libopencm3/stm32/timer.h
+++ b/include/libopencm3/stm32/timer.h
@@ -854,6 +854,7 @@ enum tim_oc_mode {
 /* --- TIM functions ------------------------------------------------------- */
 void timer_enable_irq(u32 timer_peripheral, u32 irq);
 void timer_disable_irq(u32 timer_peripheral, u32 irq);
+void timer_clear_flag(u32 timer_peripheral, u32 flag);
 void timer_set_mode(u32 timer_peripheral, u8 clock_div,
 		    u8 alignment, u8 direction);
 void timer_set_clock_division(u32 timer_peripheral, u32 clock_div);
diff --git a/lib/stm32/timer.c b/lib/stm32/timer.c
index 15e3b148..8c612ed5 100644
--- a/lib/stm32/timer.c
+++ b/lib/stm32/timer.c
@@ -37,6 +37,11 @@ void timer_disable_irq(u32 timer_peripheral, u32 irq)
 	TIM_DIER(timer_peripheral) &= ~irq;
 }
 
+void timer_clear_flag(u32 timer_peripheral, u32 flag)
+{
+	TIM_SR(timer_peripheral) &= ~flag;
+}
+
 void timer_set_mode(u32 timer_peripheral, u8 clock_div,
 		    u8 alignment, u8 direction)
 {