diff --git a/core/net/mac/tsch/tsch-slot-operation.c b/core/net/mac/tsch/tsch-slot-operation.c
index 7c3257c84..62e7f0efd 100644
--- a/core/net/mac/tsch/tsch-slot-operation.c
+++ b/core/net/mac/tsch/tsch-slot-operation.c
@@ -737,7 +737,7 @@ PT_THREAD(tsch_rx_slot(struct pt *pt, struct rtimer *t))
           if(linkaddr_cmp(&destination_address, &linkaddr_node_addr)
              || linkaddr_cmp(&destination_address, &linkaddr_null)) {
             int do_nack = 0;
-            estimated_drift = ((int32_t)expected_rx_time - (int32_t)rx_start_time);
+            estimated_drift = RTIMER_CLOCK_DIFF(expected_rx_time, rx_start_time);
 
 #if TSCH_TIMESYNC_REMOVE_JITTER
             /* remove jitter due to measurement errors */
diff --git a/core/sys/rtimer.h b/core/sys/rtimer.h
index 91c23b932..a89ed8299 100644
--- a/core/sys/rtimer.h
+++ b/core/sys/rtimer.h
@@ -55,10 +55,12 @@
 
 #include "contiki-conf.h"
 
-#ifndef RTIMER_CLOCK_LT
+#ifndef RTIMER_CLOCK_DIFF
 typedef unsigned short rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a,b)     ((signed short)((a)-(b)) < 0)
-#endif /* RTIMER_CLOCK_LT */
+#define RTIMER_CLOCK_DIFF(a,b)     ((signed short)((a)-(b)))
+#endif /* RTIMER_CLOCK_DIFF */
+
+#define RTIMER_CLOCK_LT(a, b)      (RTIMER_CLOCK_DIFF((a),(b)) < 0)
 
 #include "rtimer-arch.h"
 
diff --git a/cpu/arm/aducrf101/aducrf101-contiki.h b/cpu/arm/aducrf101/aducrf101-contiki.h
index 00fd8765d..4610c49d6 100644
--- a/cpu/arm/aducrf101/aducrf101-contiki.h
+++ b/cpu/arm/aducrf101/aducrf101-contiki.h
@@ -46,7 +46,7 @@ typedef uint32_t clock_time_t;
 typedef uint16_t uip_stats_t;
 
 typedef uint32_t rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a, b)  ((int32_t)((a) - (b)) < 0)
+#define RTIMER_CLOCK_DIFF(a, b)  ((int32_t)((a) - (b)))
 rtimer_clock_t rtimer_arch_now(void);
 
 #endif
diff --git a/cpu/mc1322x/contiki-mc1322x-conf.h b/cpu/mc1322x/contiki-mc1322x-conf.h
index e6c65df56..2dfb7e0f1 100644
--- a/cpu/mc1322x/contiki-mc1322x-conf.h
+++ b/cpu/mc1322x/contiki-mc1322x-conf.h
@@ -55,8 +55,8 @@ typedef unsigned short uip_stats_t;
 
 typedef uint32_t clock_time_t;
 
-/* Core rtimer.h defaults to 16 bit timer unless RTIMER_CLOCK_LT is defined */
+/* Core rtimer.h defaults to 16 bit timer unless RTIMER_CLOCK_DIFF is defined */
 typedef unsigned long rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a,b)     ((signed long)((a)-(b)) < 0)
+#define RTIMER_CLOCK_DIFF(a,b)     ((signed long)((a)-(b)))
 
 #endif
diff --git a/platform/cc2538dk/contiki-conf.h b/platform/cc2538dk/contiki-conf.h
index ad9aafeeb..9d18ec344 100644
--- a/platform/cc2538dk/contiki-conf.h
+++ b/platform/cc2538dk/contiki-conf.h
@@ -34,10 +34,10 @@ typedef uint32_t uip_stats_t;
 
 /*
  * rtimer.h typedefs rtimer_clock_t as unsigned short. We need to define
- * RTIMER_CLOCK_LT to override this
+ * RTIMER_CLOCK_DIFF to override this
  */
 typedef uint32_t rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a,b)     ((int32_t)((a)-(b)) < 0)
+#define RTIMER_CLOCK_DIFF(a,b)     ((int32_t)((a)-(b)))
 /** @} */
 /*---------------------------------------------------------------------------*/
 /**
diff --git a/platform/cooja/contiki-conf.h b/platform/cooja/contiki-conf.h
index dba7e9553..f4972d28f 100644
--- a/platform/cooja/contiki-conf.h
+++ b/platform/cooja/contiki-conf.h
@@ -198,7 +198,7 @@ typedef unsigned short uip_stats_t;
 #define CLOCK_CONF_SECOND 1000L
 typedef unsigned long clock_time_t;
 typedef unsigned long rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a,b)     ((signed long)((a)-(b)) < 0)
+#define RTIMER_CLOCK_DIFF(a,b)     ((signed long)((a)-(b)))
 
 #define AODV_COMPLIANCE
 #define AODV_NUM_RT_ENTRIES 32
diff --git a/platform/galileo/contiki-conf.h b/platform/galileo/contiki-conf.h
index dca42b8de..2d64c440f 100644
--- a/platform/galileo/contiki-conf.h
+++ b/platform/galileo/contiki-conf.h
@@ -46,7 +46,7 @@ typedef unsigned long clock_time_t;
 
 typedef uint64_t rtimer_clock_t;
 #define RTIMER_ARCH_SECOND 1024
-#define RTIMER_CLOCK_LT(a, b)     ((int64_t)((a) - (b)) < 0)
+#define RTIMER_CLOCK_DIFF(a, b)     ((int64_t)((a) - (b)))
 
 /* We define the following macros and types otherwise Contiki does not
  * compile.
diff --git a/platform/jn516x/platform-conf.h b/platform/jn516x/platform-conf.h
index c1c372b64..408b4957e 100644
--- a/platform/jn516x/platform-conf.h
+++ b/platform/jn516x/platform-conf.h
@@ -80,9 +80,9 @@
 #define JN516X_EXTERNAL_CRYSTAL_OSCILLATOR (RTIMER_USE_32KHZ || JN516X_SLEEP_ENABLED)
 #endif /* JN516X_EXTERNAL_CRYSTAL_OSCILLATOR */
 
-/* Core rtimer.h defaults to 16 bit timer unless RTIMER_CLOCK_LT is defined */
+/* Core rtimer.h defaults to 16 bit timer unless RTIMER_CLOCK_DIFF is defined */
 typedef uint32_t rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a, b)     ((int32_t)((a) - (b)) < 0)
+#define RTIMER_CLOCK_DIFF(a, b)     ((int32_t)((a) - (b)))
 
 /* 8ms timer tick */
 #define CLOCK_CONF_SECOND 125
diff --git a/platform/mbxxx/platform-conf.h b/platform/mbxxx/platform-conf.h
index 6b811ec96..98870980d 100644
--- a/platform/mbxxx/platform-conf.h
+++ b/platform/mbxxx/platform-conf.h
@@ -87,7 +87,7 @@ typedef unsigned long clock_time_t;
 
 typedef unsigned long rtimer_clock_t;
 
-#define RTIMER_CLOCK_LT(a,b)     ((signed long)((a)-(b)) < 0)
+#define RTIMER_CLOCK_DIFF(a,b)     ((signed long)((a)-(b)))
 
 #define LEDS_CONF_RED_PIN     boardDescription->io->leds[1].gpioPin
 #define LEDS_CONF_GREEN_PIN   boardDescription->io->leds[0].gpioPin
diff --git a/platform/openmote-cc2538/contiki-conf.h b/platform/openmote-cc2538/contiki-conf.h
index 6c0349025..87b58f299 100644
--- a/platform/openmote-cc2538/contiki-conf.h
+++ b/platform/openmote-cc2538/contiki-conf.h
@@ -73,10 +73,10 @@ typedef uint32_t uip_stats_t;
 
 /*
  * rtimer.h typedefs rtimer_clock_t as unsigned short. We need to define
- * RTIMER_CLOCK_LT to override this
+ * RTIMER_CLOCK_DIFF to override this
  */
 typedef uint32_t rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a, b)     ((int32_t)((a) - (b)) < 0)
+#define RTIMER_CLOCK_DIFF(a, b)     ((int32_t)((a) - (b)))
 /** @} */
 /*---------------------------------------------------------------------------*/
 /**
diff --git a/platform/seedeye/contiki-conf.h b/platform/seedeye/contiki-conf.h
index 69c788381..d58ff686d 100644
--- a/platform/seedeye/contiki-conf.h
+++ b/platform/seedeye/contiki-conf.h
@@ -60,7 +60,7 @@ typedef uint16_t uip_stats_t;
 typedef uint32_t clock_time_t;
 
 typedef uint32_t rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a,b) ((int32_t)((a)-(b)) < 0)
+#define RTIMER_CLOCK_DIFF(a,b) ((int32_t)((a)-(b)))
 
 #define RF_CHANNEL                              13
 
diff --git a/platform/srf06-cc26xx/contiki-conf.h b/platform/srf06-cc26xx/contiki-conf.h
index 79c1d479a..6e52b5c0c 100644
--- a/platform/srf06-cc26xx/contiki-conf.h
+++ b/platform/srf06-cc26xx/contiki-conf.h
@@ -325,10 +325,10 @@ typedef uint32_t uip_stats_t;
 
 /*
  * rtimer.h typedefs rtimer_clock_t as unsigned short. We need to define
- * RTIMER_CLOCK_LT to override this
+ * RTIMER_CLOCK_DIFF to override this
  */
 typedef uint32_t rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a, b)     ((int32_t)((a) - (b)) < 0)
+#define RTIMER_CLOCK_DIFF(a, b)     ((int32_t)((a) - (b)))
 /** @} */
 /*---------------------------------------------------------------------------*/
 /* board.h assumes that basic configuration is done */
diff --git a/platform/stm32nucleo-spirit1/platform-conf.h b/platform/stm32nucleo-spirit1/platform-conf.h
index dede0bdeb..0f2a0077b 100644
--- a/platform/stm32nucleo-spirit1/platform-conf.h
+++ b/platform/stm32nucleo-spirit1/platform-conf.h
@@ -78,7 +78,7 @@
 #define CLOCK_CONF_SECOND             128
 /* One tick: 62.5 ms */
 
-#define RTIMER_CLOCK_LT(a, b)     ((signed short)((a) - (b)) < 0)
+#define RTIMER_CLOCK_DIFF(a, b)     ((signed short)((a) - (b)))
 /*---------------------------------------------------------------------------*/
 typedef unsigned long clock_time_t;
 typedef unsigned long long rtimer_clock_t;
diff --git a/platform/zoul/contiki-conf.h b/platform/zoul/contiki-conf.h
index 2c2bcb854..3d07103ef 100644
--- a/platform/zoul/contiki-conf.h
+++ b/platform/zoul/contiki-conf.h
@@ -71,10 +71,10 @@ typedef uint32_t uip_stats_t;
 
 /*
  * rtimer.h typedefs rtimer_clock_t as unsigned short. We need to define
- * RTIMER_CLOCK_LT to override this
+ * RTIMER_CLOCK_DIFF to override this
  */
 typedef uint32_t rtimer_clock_t;
-#define RTIMER_CLOCK_LT(a, b)     ((int32_t)((a) - (b)) < 0)
+#define RTIMER_CLOCK_DIFF(a, b)     ((int32_t)((a) - (b)))
 /** @} */
 /*---------------------------------------------------------------------------*/
 /**