diff --git a/core/sys/timer.c b/core/sys/timer.c
index 821f2a2bc..756ea4759 100644
--- a/core/sys/timer.c
+++ b/core/sys/timer.c
@@ -42,7 +42,7 @@
  *
  * Author: Adam Dunkels <adam@sics.se>
  *
- * $Id: timer.c,v 1.5 2009/01/24 15:20:11 adamdunkels Exp $
+ * $Id: timer.c,v 1.6 2010/02/23 18:40:08 adamdunkels Exp $
  */
 
 #include "contiki-conf.h"
@@ -121,7 +121,10 @@ timer_restart(struct timer *t)
 int
 timer_expired(struct timer *t)
 {
-  return (clock_time_t)(clock_time() - t->start) >= (clock_time_t)t->interval;
+  clock_time_t diff = clock_time() - t->start;
+  /* This somewhat ugly way of returning (diff >= t->interval) is
+     required to avoid an internal error in mspgcc. */
+  return diff > t->interval || diff == t->interval;
 }
 /*---------------------------------------------------------------------------*/
 /**