diff --git a/stmhal/irq.h b/stmhal/irq.h
index f3a8a2cc9e..5a08a7d501 100644
--- a/stmhal/irq.h
+++ b/stmhal/irq.h
@@ -126,9 +126,6 @@ MP_DECLARE_CONST_FUN_OBJ(pyb_irq_stats_obj);
 #define IRQ_PRI_OTG_HS          6
 #define IRQ_SUBPRI_OTG_HS                   0
 
-#define IRQ_PRI_TIM3            6
-#define IRQ_SUBPRI_TIM3                     0
-
 #define IRQ_PRI_TIM5            6
 #define IRQ_SUBPRI_TIM5                     0
 
diff --git a/stmhal/timer.c b/stmhal/timer.c
index e8b29eb97f..5727a95b73 100644
--- a/stmhal/timer.c
+++ b/stmhal/timer.c
@@ -601,7 +601,7 @@ STATIC mp_obj_t pyb_timer_init_helper(pyb_timer_obj_t *self, mp_uint_t n_args, c
     }
 
     // set IRQ priority (if not a special timer)
-    if (self->tim_id != 3 && self->tim_id != 5) {
+    if (self->tim_id != 5) {
         HAL_NVIC_SetPriority(self->irqn, IRQ_PRI_TIMX, IRQ_SUBPRI_TIMX);
         if (self->tim_id == 1) {
             HAL_NVIC_SetPriority(TIM1_CC_IRQn, IRQ_PRI_TIMX, IRQ_SUBPRI_TIMX);