diff --git a/arch/arm/src/stm32h7/Make.defs b/arch/arm/src/stm32h7/Make.defs
index c36ec04dc0..2092016cbe 100644
--- a/arch/arm/src/stm32h7/Make.defs
+++ b/arch/arm/src/stm32h7/Make.defs
@@ -90,10 +90,10 @@ CHIP_CSRCS  = stm32_allocateheap.c stm32_exti_gpio.c stm32_gpio.c stm32_irq.c
 CHIP_CSRCS += stm32_start.c stm32_rcc.c stm32_lowputc.c stm32_serial.c
 CHIP_CSRCS += stm32_uid.c
 
-ifneq ($(CONFIG_SCHED_TICKLESS),y)
-CHIP_CSRCS += stm32_timerisr.c
-else
+ifeq ($(CONFIG_SCHED_TICKLESS),y)
 CHIP_CSRCS += stm32_tickless.c
+else
+CHIP_CSRCS += stm32_timerisr.c
 endif
 
 ifeq ($(CONFIG_STM32H7_ONESHOT),y)
diff --git a/arch/arm/src/stm32h7/stm32_tickless.c b/arch/arm/src/stm32h7/stm32_tickless.c
index d529384a6e..a341403499 100644
--- a/arch/arm/src/stm32h7/stm32_tickless.c
+++ b/arch/arm/src/stm32h7/stm32_tickless.c
@@ -541,10 +541,10 @@ void up_timer_initialize(void)
   g_tickless.overflow  = 0;
 
   tmrinfo("timer=%d channel=%d frequency=%lu Hz\n",
-           g_tickless.timer, g_tickless.channel, g_tickless.frequency);
+          g_tickless.timer, g_tickless.channel, g_tickless.frequency);
 
   g_tickless.tch = stm32_tim_init(g_tickless.timer);
-  if (!g_tickless.tch)
+  if (g_tickless.tch == NULL)
     {
       tmrerr("ERROR: Failed to allocate TIM%d\n", g_tickless.timer);
       DEBUGASSERT(0);
@@ -640,7 +640,7 @@ int up_timer_gettime(FAR struct timespec *ts)
 
   /* Timer not initialized yet, return zero */
 
-  if (g_tickless.tch == 0)
+  if (g_tickless.tch == NULL)
     {
       ts->tv_nsec = 0;
       ts->tv_sec  = 0;
@@ -817,7 +817,7 @@ int up_timer_cancel(FAR struct timespec *ts)
        * (as when pre-emption is enabled and disabled).
        */
 
-      if (ts)
+      if (ts != NULL)
         {
           ts->tv_sec  = 0;
           ts->tv_nsec = 0;