diff --git a/os/nil/include/nil.h b/os/nil/include/nil.h
index 161c79a6d..6c3084153 100644
--- a/os/nil/include/nil.h
+++ b/os/nil/include/nil.h
@@ -735,7 +735,7 @@ typedef struct {
  * @xclass
  */
 #define chVTTimeElapsedSinceX(start)                                        \
-  ((systime_t)(chVTGetSystemTimeX() - start))
+  ((systime_t)(chVTGetSystemTimeX() - (start)))
 
 /**
  * @brief   Checks if the specified time is within the specified time window.
@@ -752,7 +752,7 @@ typedef struct {
  * @xclass
  */
 #define chVTIsTimeWithinX(time, start, end)                                 \
-  ((bool)((time) - (start) < (end) - (start)))
+  ((bool)((systime_t)((time) - (start)) < (systime_t)((end) - (start))))
 
 /**
  * @brief   Condition assertion.
diff --git a/os/nil/src/nil.c b/os/nil/src/nil.c
index 789256127..d7afe3b87 100644
--- a/os/nil/src/nil.c
+++ b/os/nil/src/nil.c
@@ -197,7 +197,7 @@ void chSysTimerHandlerI(void) {
         chSchReadyI(tp, MSG_TIMEOUT);
       }
       else {
-        if (tp->timeout <= next - 1)
+        if (tp->timeout <= (systime_t)(next - 1))
           next = tp->timeout;
       }
     }