diff --git a/STM32F1/system/libmaple/include/libmaple/timer.h b/STM32F1/system/libmaple/include/libmaple/timer.h
index e9a49e9..0c2e027 100644
--- a/STM32F1/system/libmaple/include/libmaple/timer.h
+++ b/STM32F1/system/libmaple/include/libmaple/timer.h
@@ -843,8 +843,7 @@ static inline void timer_dma_disable_req(timer_dev *dev, uint8 channel) {
  */
 static inline void timer_enable_irq(timer_dev *dev, uint8 interrupt) {
     // clear interrupt flag, use different masks for reserved bits
-    dev->regs->SR = (~BIT(interrupt)) & ( (dev->type==TIMER_ADVANCED) ? 0x1EFF : 
-                         ( (dev->type==TIMER_GENERAL) ? 0x1E5F : 0x0001) );
+    *bb_perip(&(dev->regs).adv->SR, interrupt) = 0; // clear interrupt flag
     *bb_perip(&(dev->regs).adv->DIER, interrupt) = 1;
 }