diff --git a/firmware/target/arm/as3525/kernel-as3525.c b/firmware/target/arm/as3525/kernel-as3525.c
index 3a4a067b6c..3252e5abd1 100644
--- a/firmware/target/arm/as3525/kernel-as3525.c
+++ b/firmware/target/arm/as3525/kernel-as3525.c
@@ -48,7 +48,7 @@ void tick_start(unsigned int interval_in_ms)
         panicf("%s : interval too big", __func__);
 
     CGU_PERI |= CGU_TIMER2_CLOCK_ENABLE;    /* enable peripheral */
-    VIC_INT_ENABLE = INTERRUPT_TIMER2;      /* enable interrupt */
+    VIC_INT_ENABLE |= INTERRUPT_TIMER2;     /* enable interrupt */
 
     TIMER2_LOAD = TIMER2_BGLOAD = cycles;   /* timer period */
 
diff --git a/firmware/timer.c b/firmware/timer.c
index 0746b05e46..a11cd10b7e 100644
--- a/firmware/timer.c
+++ b/firmware/timer.c
@@ -357,7 +357,7 @@ void timer_unregister(void)
     irq_disable_int(IRQ_TIMER1);
 #elif CONFIG_CPU == AS3525
     TIMER1_CONTROL &= 0x10; /* disable timer 1 (don't modify bit 4) */
-    VIC_INT_EN_CLEAR |= INTERRUPT_TIMER1;  /* disable interrupt */
+    VIC_INT_EN_CLEAR = INTERRUPT_TIMER1;  /* disable interrupt */
     CGU_PERI &= ~CGU_TIMER1_CLOCK_ENABLE;   /* disable peripheral */
 #elif CONFIG_CPU == S3C2440 || CONFIG_CPU == DM320
     __TIMER_UNREGISTER();