-#define USEC_PER_SEC 1000000
-#define DEFAULT_USER_TIMEOUT 60 // sec
-#define CLOCK_GRANULARITY 1000 // usec
-#define START_RTO 1000000 // usec
-#define MAX_RTO 3000000 // usec
+static const long USEC_PER_SEC = 1000000;
+static const long NSEC_PER_SEC = 1000000000;
+static const int DEFAULT_USER_TIMEOUT = 60; // sec
+static const long START_RTO = 1 * USEC_PER_SEC; // usec
+static const long MAX_RTO = 3 * USEC_PER_SEC; // usec