diff --git a/include/sigar_private.h b/include/sigar_private.h
index 2362fa43..99145273 100644
--- a/include/sigar_private.h
+++ b/include/sigar_private.h
@@ -101,15 +101,14 @@
 #endif
 
 #define SIGAR_MSEC 1000L
+#define SIGAR_NSEC 1000000000L
 
 #define SIGAR_SEC2NANO(s) \
-    ((sigar_uint64_t)(s) * (sigar_uint64_t)1000000000)
-
-/* cpu ticks to seconds */
-#define SIGAR_TICK2SEC(s) ((s) / sigar->ticks)
+    ((sigar_uint64_t)(s) * (sigar_uint64_t)SIGAR_NSEC)
 
 /* cpu ticks to milliseconds */
 #define SIGAR_TICK2MSEC(s) ((s) * (SIGAR_MSEC / sigar->ticks))
+#define SIGAR_TICK2NSEC(s) ((sigar_uint64_t)(s) * ((sigar_uint64_t)SIGAR_NSEC / sigar->ticks))
 
 #define IFTYPE_LO  2
 #define IFTYPE_ETH 3