diff --git a/core/lib/sensors.h b/core/lib/sensors.h
index acc41ffd1..cd717ada6 100644
--- a/core/lib/sensors.h
+++ b/core/lib/sensors.h
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * @(#)$Id: sensors.h,v 1.4 2010/01/14 13:55:21 nifi Exp $
+ * @(#)$Id: sensors.h,v 1.5 2010/01/14 14:17:08 nifi Exp $
  */
 
 #ifndef __SENSORS_H__
@@ -41,8 +41,10 @@
 #define SENSORS_ACTIVE 129 /* ACTIVE => 0 -> turn off, 1 -> turn on */
 #define SENSORS_READY 130 /* read only */
 
-#define SENSORS_ACTIVATE(sensor) sensor.configure(SENSORS_ACTIVE, (void*)1)
-#define SENSORS_DEACTIVATE(sensor) sensor.configure(SENSORS_ACTIVE, (void*)0)
+#define SENSORS_ACTIVATE(sensor)                \
+(sensor)->configure(SENSORS_ACTIVE, (void *)1)
+#define SENSORS_DEACTIVATE(sensor)              \
+(sensor)->configure(SENSORS_ACTIVE, (void *)0)
 
 #define SENSORS_SENSOR(name, type, value, configure, status)        \
 const struct sensors_sensor name = { type, value, configure, status }