diff --git a/cpu/cc26xx-cc13xx/rtimer-arch.h b/cpu/cc26xx-cc13xx/rtimer-arch.h
index 0d54d227c..128461c8d 100644
--- a/cpu/cc26xx-cc13xx/rtimer-arch.h
+++ b/cpu/cc26xx-cc13xx/rtimer-arch.h
@@ -50,6 +50,21 @@
 #define RTIMER_ARCH_SECOND 65536
 /*---------------------------------------------------------------------------*/
 rtimer_clock_t rtimer_arch_now(void);
+
+/* HW oscillator frequency is 32 kHz, not 64 kHz and RTIMER_NOW() never returns
+ * an odd value; so US_TO_RTIMERTICKS always rounds to the nearest even number.
+ */
+#define US_TO_RTIMERTICKS(US)  (2 * ((US) >= 0 ?                        \
+                               (((int32_t)(US) * (RTIMER_ARCH_SECOND / 2) + 500000) / 1000000L) :      \
+                                ((int32_t)(US) * (RTIMER_ARCH_SECOND / 2) - 500000) / 1000000L))
+
+#define RTIMERTICKS_TO_US(T)   ((T) >= 0 ?                     \
+                               (((int32_t)(T) * 1000000L + ((RTIMER_ARCH_SECOND) / 2)) / (RTIMER_ARCH_SECOND)) : \
+                               ((int32_t)(T) * 1000000L - ((RTIMER_ARCH_SECOND) / 2)) / (RTIMER_ARCH_SECOND))
+
+/* A 64-bit version because the 32-bit one cannot handle T >= 4295 ticks.
+   Intended only for positive values of T. */
+#define RTIMERTICKS_TO_US_64(T)  ((uint32_t)(((uint64_t)(T) * 1000000 + ((RTIMER_ARCH_SECOND) / 2)) / (RTIMER_ARCH_SECOND)))
 /*---------------------------------------------------------------------------*/
 #endif /* RTIMER_ARCH_H_ */
 /*---------------------------------------------------------------------------*/